ENVIRONMENT AND HEALTH

ENVIRONMENT AND HEALTH

METHOD OF HYGIENICAL ESTIMATION OF INFLUENCING OF WEATHER ON A HEALTH OF A HUMAN. ACCLIMATIZATION. PROPHYLAXIS OF METEOTROPIC REACTIONS] SANITARY CLEANING OF THE INHABITED PLACES. A GENERAL CHART AND BUILDINGS FOR DISPOSAL OF SEWAGE

Weather

The weather is a complex of physical features of the nearland atmospheric layer during a relatively short period of time (hours, days, weeks). The weather is characterized by the complex of meteorological elements: solar irradiation, temperature, humidity, air speed and direction, atmospheric pressure, electrical condition of the atmosphere, cloudiness and the presence of precipitations.

Consequently, the weather is a changeable process, as the climate is stable one and it has a prolonged influence upon the human organism.

Weather is a compound of physical properties of near Erath atmosphere till a short period of time (hour, day, week).

Weather as a changable nature is formed in consequence of nature (sun irradiation, circulation of air masses) and human (pollution of atmosphere, distroying of woods, creating of artificial lakes, irigation e.t.c.) factor conetctions.

Weather is characterized with a complex of heliophysical (intensity of sun radiation), geophysical (voltage of atmosphere electric field, atmospheric ionisation), meteorological (temperature air, atmospheric pressure, speed and course of wind), synoptic (clouds, rainings and snowings) and chemical (composition of near Earth layer of atmosphere) actions.

Weather has a profound effect on human health and well-being. It has been demonstrated that weather is associated with changes in birth rates, with outbreaks of pneumonia, influenza and bronchitis, and is related to other morbi dity effects linked to pollen concentrations and high pollution levels.

Climate and weather as combination of environmental factors

 

Weather is the physical and chemical characteristics of the bottom layer during the short period of time (hours, days, weeks) (Weather is the day-to-day meteorological conditions experienced in a place or area).

Climate is long-term weather regime, repeating in the particular region systematically (Climate is the long-term prevailing weather conditions in an area).

So, weather is the changeable phenomenon, while climate is the statistically permanent phenomenon characterizing the particular region.

The weather forming factors:

1. Natural:

The solar radiation intensity (total and erythematous UV radiation, solar illumination duration) and the solar activity (solar spots, active regions, chromospheric bursts, radio-wave radiation);

The type of underlying surface (snow, water, soil etc.);

The atmospheric motion (cyclones, anticyclones, atmospheric fronts, trades, monsoon etc.).

2. Antropogenic:

The atmosphere pollution by industrial waste (smog);

The destruction of the woods, land reclamation (melioration), irrigation, formation of artificial reservoirs;

The weather type depends on region climate and time of the year.

The weather characterizing factors:

1.   Heliophysical:

- the solar radiation intensity (total and erythematous UV radiation, the solar illumination duration);

- the solar activity (solar spots, active regions, chromospheric bursts, radio-wave radiation);

2. Geophysical:

- the planet and abnormal geomagnetic intensity, geomagnetic storms, impulses.

3. Atmospheric electricity:

- the atmospheric electric field intensity, atmospheric electroconductivity, air ionization, electromagnetic oscillation and discharges.

4. Meteorological factors:

- air temperature, surface radiation temperature;

- air humidity;

- direction and air movement speed;

- atmospheric pressure.

5. Synoptic phenomena:

- the cloudiness, precipitations and their characteristics (rain, snow etc.).

6. Chemical characteristics of the bottom layer:

- concentrations of oxygen, carbon dioxide, atmospheric pollutants.

The climate forming factors:

The geographical latitude of the region determinates the sun-raising above the horizon, the solar radiation intensity per earth surface;

The height above sea level and the relief (flat and undulating grounds, highlands);

The surface type (forests, forest-steppes, steppes, deserts, water reservoirs);

The closeness to seas, oceans, the type of the nearby sea currents (warm, e.g. Gulf Stream, cool, e.g. Labrador Current);

The air circulation types (cyclones, anticyclones, atmospheric fronts, trades, monsoon, wind strength and duration, that dominate in the region, for example phene, north, bora, sirocco ect.).

The climate characterizing factors:

1. Regional temperature conditions are characterized by the following parameters:

- the absolute minimum temperature;

- the absolute maximum temperature;

- the average annual temperature amplitude (range);

- the average temperature of January;

- the average temperature of July;

- the average annual temperature.

2. Air humidity is characterized by the following parameters:

- the minimum humidity;

- the maximum humidity;

- the average annual humidity;

- the annual amount and character of precipitations (rain, snow);

- the average mouth precipitations;

- the total days with precipitations;

- the average days with precipitations during the month;

- the total number of dry-days (without the precipitations) during the year;

- the total number of moist-days (rainy, snowy) during the year.

3. Atmospheric pressure is characterized by the following parameters:

- the minimum pressure;

- the maximum pressure;

- the average annual pressure;

- the amplitude of pressure difference.

4. Air movement direction and speed is characterized by the following parameters;

- the region wind rose, the windy and calm days ratio during the year;

- the maximum air movement speed;

- the average annual wind speed.

5. The light climate is characterized by the following parameters:

- the monthly average minimum horizontal illumination;

- the monthly average maximum horizontal illumination;

- the average annual horizontal illumination;

- the total annual number of sunny days;

- the month with maximum sunny days;

- the month with minimum sunny days;

- the monthly average minimum intensity of the solar radiation;

- the monthly average maximum intensity of the solar radiation;

- the average annual intensity of the solar radiation.

6. The soil:

- soil types: dry, swamped soils;

- the frost zone of the soil;

- the duration of snow cover deposition;

- the duration of heating season.

 

Classifications of the weather and the climate

 

From the point of view of prevention of different types of diseases, the climate and the weather classifications, including medical are significant.

The climate conditions of the region are characterized by certain geographical particularities. The seven main climate zones are defined in accordance to the main geographical characteristics (temperature, pressure, air humidity, precipitations, light climate, wind parameters) and the geographical latitude of the region (see table 1).

 

Table 1

The Earth climate classification

 

Name of the climate zone

Geographical latitude

Average annual temperature

Surface type

1. Tropical

13 latitude

+20-24

Evergreen forests, jungle

2. Hot

13-26 --

+16-20

Forests, steppe, desert

3. Warm

26-39 --

+12-16

Forests, steppe, desert

4. Moderate

39-52 --

+8-12

Forest-steppe

5. Cold

52-65 --

+4-18

Forests

6. Inclement

65-78 --

0-4

Forests, tundra

7. Arctic (polar)

69-90 --

-4 and below

Tundra

The relief (flat and undulating grounds, highlands) and height above the see level are of great importance.

 

The five climate zones can be defined in the Ukraine: the marshy woodlands, forest-steppe, steppe, the Carpathian Mountains, the south coast of the Crimea (see table 2).

The climate zoning of the CIS (ex-USSR) territory (building climate classification) is presented in the table 3.

The zoning of the Ukraine territory is used for weather forecast in weather bureau: the north part (Zhytomyr, Kyiv, Chernihiv and Sumy regions), the west part (Lviv, Zakarpattya, Ivano-Frankivsk, Ternopil, Khmelnytskyy and Chernivci regions), the central part (Vinnytsya, Cherkasy, Poltava, Kirovograd and Dnipropetrovsk regions), the east part (Kharkiv, Lugansk and Donetsk regions) and the south part (Odesa, Mykolayiv, Kherson and Zaporizhzhya regions) and the Crimea the steppe part of the Ukraine. The south coast of the Crimea is considered as a separate climate zone.


Table 4

 

Medical weather classification by I.I. Grigorev

 

The weather types

The weather characteristics

The most comfortable

The stable weather is determined by anticyclone without considerable cloudiness and precipitations. The atmospheric pressure is higher that 760 Hg mm, an atmospheric difference is near 5 Hg mm, an air movement speed is to 3.0 m/sec, oxygen concentration above 315 mg/l.

Comfortable

Insignificant regional changes of the weather due to short-term precipitations and the variable cloudiness. An atmospheric pressure is 760-755 Hg mm, an atmospheric difference - 6-8 Hg mm, an air movement speed 4.0-7.0 m/sec, a temperature difference to - 50, oxygen concentration - below 315 mg/l.

The weather requires intensified medical control (supervision)

A cloudy unstable weather with precipitations, frequently caused by moderate cyclones and local thunderstorms. An atmospheric pressure is 754-745 Hg mm, an atmospheric difference is 9.0 14.0 Hg mm, air movement speed is 8.0 10.0 m/sec, a temperature difference is 6 - 90, oxygen concentration is 260 - 289 mg/l.

The weather requires severe medical control (supervision)

The weather is with storms and intensive precipitations, caused by deep cyclone. An atmospheric pressure is to 745 Hg mm, a pressure difference is above 14 Hg mm, a temperature difference above 100, oxygen concentration - below 260 mg/l.


Table 2

 

Classification of the climate of the Ukraine

 

Name of the zone

Zone limit

Temperatures, 0

Precipitations, mm

Total days with precipitations

Average air

humidity

Duration of snow cover

Average in January

Average in July

Average annual

Minimum

Maximum

1. Marshy woodlands

In the north: borders of the Ukraine. In the south: Lutsk, Shepetivka, Zhytomyr, Kyiv, Nizhyn, Konotop.

-4.5-7.80

+17-180 +19-200

5.5-7.00

-32-350

+35-360

500-600

170-190

30-60%

100-110 days

2. Forest- steppe

In the north: Lutsk, etc.. In the south: Kotovsk, irovograd, remenchuh, Poltava, Kharkiv

-7-80

+18-210

+11-140

-310

+35-380

500-700

150-170

30-60%

90-100 days

3. Steppe

In the north: Kotovsk, etc.. In the south: coasts of the Black and Azov seas (except the south coast of the Crimea)

-5-20

+20-210

+12-150

-300

+400

250-300

120-150

Frequent hot winds

70-90 days

4. The Carpathian Mountains

The Carpathian Mountains and nearest hills

-7-80

+18-210

+14-150

-260

+310

800-900

180-200

60-75%

60-70 days

5. The south coast of the Crimea

The south hills of the Crimean Mountains and seashore

+40

+240

+15-160

-100

+400

400

130-160

60-64%

0-30 days

 

Table 3

 

Classification of the climate of the CIS (ex-USSR) territory (building climate classification)

 

The climate

Temperature and humidity characteristics of the subregions

Average wind speed, m/sec

region

subregion

Average air temperature in January (0)

Average air temperature in July (0)

Average relative air humidity in July (%)

Precipitations (mm during the year)

Prevailing wind direction

B

C

D

E

-32 and below

-28 till -32

-14 till -28

-14 till -28

-28 till -32

4 till 19

0 till +13

+12 till +21

0 till +14

+10 till +21

ignor.

above 75

ignor.

above 75

ignor.

192

206

406

456

496

N-NE

N-NE

N-NE

E

E

ignor.

5 and above

ignor.

5 and above

ignor.

B

C

-4 till -14

-3 till -5

-4 till -14

+8 till +12

+12 till +21

+12 till +21

above 75

above 75

ignor.

582

605

494

NE

W

N

5 and above

5 and above

ignor.

B

C

-2 till -20

-5 till +2

-5 till -14

+21 till +25

+21 till +25

+21 till +25

ignor.

ignor.

ignor.

295

310

318

NE

W

NE

ignor.

ignor.

ignor.

V

IV

IV B

IV C

IV D

-10 till +2

+2 till +6

0 till +2

-15 till 0

+28 and above

+22 till +28

+25 till +28

+25 till +28

ignor.

50 and above

ignor.

ignor.

244

100 3

4 - 98 3

4 - 98

E

E

NE

NE

ignor.

ignor.

ignor.

ignor.


Table 5

Medical weather classification by G.P. Fedorov

The weather type

Meteorological characteristics

Air temperature difference, 0

Relative

air humidity, %

Air movement speed, m/sec

Air pressure

difference, gPa

Optimal

2

40 - 70

3

3

Irritant

2 - 4

70 - 90

3 - 9

4 - 8

Acute

above 4

above 90

above 9

above 8

 

Recent researches (see tables 8-10) conducted at the propedeutic hygiene and military hygiene department of the National medical university named after A.A. Bogomolets, have proven the considerable adequacy of the weather classifications developed under the direction of V.F. Ovcharova in the Balneology and Physiotherapy Central Institute. This classification is used for the medical forecast of meteorotropic reactions in different climate zones of Ukraine (see table 6) and includes the dynamics and the intensity of circulating processes in the air, as well as many other meteorological elements (see table 7).

The tables 8, 9, 10 are used for the hygienic assessment of the weather troposity to the acute attacks of chronic cardiovascular diseases, bronchial asthma in different climate zones of the Ukraine.

 

Table 6

Medical weather classification by V.F. Ovcharova and others

The weather characteristics from the medical view

The weather pattern characteristics

Stable indifferent

The slow-moving anticyclone without atmospheric fronts

Unstable, passing from indifferent to spastic type

Destruction of the anticyclone. An approach of an inclination, a crest, a non-gradient region with increased pressure.

 

An approach of a cold front or an occlusion front as a cold type.

Spastic type

An establishment of an inclination (ridge), a crest, a non-gradient region with increased pressure.

 

A cold frontal passage or an occlusion frontal passage as a cold type.

Unstable spastic type with elements of hypoxic type

The retreat of a cold front or an occlusion front as a cold type

 

An approach of a cyclone, a saddle, a dish, a non-gradient region with low pressure

 

An approach of a warm front or an occlusion front as a warm type

Hypoxic type

The retreat of a cyclone, a saddle, a dish, a non-gradient region with decreased (reduced) pressure

 

A warm front passage of an occlusion frontal passage as a warm type

Unstable hypoxic type with elements of spastic type of weather

An establishment of a cyclone, a saddle, a dish, a non-gradient region with decreased pressure

 

The retreat of a warm front or an occlusion front as a warm type

 

An approach of a inclination (ridge), a crest, a non-gradient region with increased pressure

Spastic type weather passing to stable indifferent

An establishment of an anticyclone after a cold front

 

A formation of a local anticyclone

 

Table 7

The weather elements interdiurnal variability

 

The main meteorological elements tendency

The intensity degree of the weather elements interdiurnal variability

indifferent

weak

moderate

variable

very variable

without particular changes

R

2

2.5

2.5

0.5

10

2.5

 

 

 

 

a +-

b -+

+-

R +-

2

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

+

a

b +

-+

R -+

2 +

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

a -+

b +-

+

R +

2 +

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

b +

R +

2 -

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

a

b +

+-

R +_

2 +-

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

+

b +

R

2 +

<2.5

<2.5

 

<0.5

<10

<2.5

2.5-5.0

2.5-5.0

 

0.5-1.0

11-20

2.5-5.0

5.1-10.0

5.1-10.0

 

1.1-2.0

21-30

5.1-10.0

10.1-20.0 10.1-20.0

 

2.1-4.0

31-40

10.1-20.0

>20.0

>20.0

 

>4.0

>40

>20.0

Conventions:

+ a transfer from depression to increase;

+ a transfer from increase to depression, a tendency to an exaggerate;

an increase;

a depression;

a winter (a cold period);

b a summer (a warm period);

n atmospheric pressure (mb);

R a relative humidity (%);

an absolute humidity (mb);

an air temperature (0C);

2 oxygen concentration in the air (g/m3)

 

Table 8

 

Hygienic assessment of the weather biotroposity to the acute attacks of hypertension strokes (I), angina pectoris (II), myocardial infarctions (III), strokes (IV) in different climate zones of the Ukraine by V.G. Bardov (1985)

 

The main meteorological elements tendency

The intensity degree of the weather elements interdiurnal variability

indiffe-rent

weak

moderate

variable

very variable

The stable indifferent

I-F

-F

-F

V-F

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

The unstable with the transfer from the indifferent into spastic type

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

I-MB

-F

-F

IV-MB

I-AT

-MB

-MB

IV-AT

I-AT

-AT

-AT

IV-AT

Spastic type

I-F

-F

-F

IV-F

I-MB

-

-

IV-MB

I-AT

-MB

-MB

IV-AT

I-AT

-AT

-AT

IV-AT

I-AT

-AT

-AT

IV-AT

The unstable spastic type with hypoxic type weather elements

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

I-MB

-F

-F

IV-MB

I-AT

-MB

-MB

IV-AT

I-AT

-AT

-AT

IV-AT

Hypoxic type

I-F

-MB

-MB

IV-F

I-MB

-AT

-AT

IV-MB

I-AT

-AT

-AT

IV-AT

I-AT

-AT

-AT

IV-AT

I-AT

-AT

-AT

IV-AT

The unstable hypoxic type with spastic type weather elements

I-F

-F

-F

IV-F

I-F

-MB

-MB

IV-F

I-MB

-AT

-MB

IV-MB

I-AT

-AT

-AT

IV-AT

I-AT

-AT

-AT

IV-AT

A transfer from a spastic type weather into a stable indifferent

I-F

-F

-F

IV-F

I-F

-F

-F

IV-F

I-MB

-MB

-MB

IV-MB

I-AT

-AT

-AT

IV-AT

I-AT

-AT

-AT

IV-AT

Conventions:

F favorable weather type for cardiovascular diseases prevention;

MB moderate biotropical weather type;

AT adverse weather type;

I HS hypertension strokes;

II AP angina pectoris;

III MI myocardial infarctions;

IV S strokes.

 

Table 9

 

Hygienic assessment of the weather biotroposity to acute attacks of bronchial asthma in different climate zones of the Ukraine by Ye.M. Anisimov (1998)

 

The main meteorological elements tendency

The intensity degree of the weather elements

interdiurnal variability

indiffe-rent

weak

moderate

variable

very variable

The stable indifferent

F

F

F

F

F

The unstable with the transfer from the indifferent into spastic type

F

F

F

AT

AT

Spastic type

F

MB

AT

AT

AT

The unstable spastic type with hypoxic type weather elements

MB

MB

AT

AT

AT

Hypoxic type

MB

AT

AT

AT

AT

The unstable hypoxic type with spastic type weather elements

MB

AT

AT

AT

AT

A transfer from a spastic type weather into a stable indifferent

F

F

F

MB

AT

Conventions:

F favourable weather type;

MB moderate biotropical weather type;

AT adverse weather type;

Table 10

 

Hygienic assessment of the weather biotroposity to acute attacks of coronary heart diseases in different climate zones of the Ukraine by S.M. Tkachenko (1999)

 

The main meteorological elements tendency

The intensity degree an interdiurnal variability of the weather elements

indiffe-rent

weak

moderate

variable

very variable

The stable indifferent

F

F

F

F

F

The unstable with the transfer from indifferent into spastic type

F

F

F

F

AT

Spastic type

F

MB

MB

AT

AT

The unstable spastic type with hypoxic type weather elements

MB

AT

AT

AT

AT

Hypoxic type

MB

MB

AT

AT

AT

The unstable hypoxic type with spastic type weather elements

MB

MB

AT

AT

AT

A transfer from a spastic type weather into a stable indifferent

MB

MB

AT

AT

AT

Conventions:

F favourable weather type;

MB moderate biotropical weather type;

AT adverse weather type.

ENERGY BALANCE IN THE ATMOSPHERE

Solar energy doesn't strike the whole globe equally. At the equator, the sun is almost directly overhead all year long. Its rays are very intense because it shines through a relatively short column of air (straight down), and energy flux (flow) is high. At the poles, however, sunlight comes in at an oblique angle. The long column of air through which light must pass before it reaches the surface causes much greater energy losses from absorption and scattering. Moreover, when the light does reach the ground, it is spread over a larger area because of its angle of incidence, reducing surface heating even more.

Furthermore, seasonal tilting of the earth's axis means that there is no sunlight at the poles during much of the winter. The equator, by contrast, has days about the same length all year long; thus, compared to the poles, the equatorial regions have an energy surplus. This energy imbalance is evened out by movement of air and water vapor in the atmosphere, and by liquid water in rivers and ocean currents. Warm, tropical air moving toward the poles and cold, polar air moving toward the equator account for about half of this energy transfer. Latent heat in water vapor (mainly from the oceans) makes up about 30 percent of the global energy redistribution. The remaining 20 percent is carried mainly by ocean currents.

Hadley Cells and Prevailing Winds

As air warms at the equator, rises, and moves northward, it doesn't go straight to the pole in a single convection current. Instead, this air sinks and rises in several intermediate bands, forming circulation patterns called Hadley cells. Nor do the returning surface flows within these cells run straight north and south. Friction, drag, and momentum cause air layers close to the earth's surface to be pulled in the direction of rotation. This deflection is called the Coriolis effect. In the Northern Hemisphere, the Coriolis effect deflects winds about 30 to the right of their expected path, creating clockwise or anticyclonic spiraling patterns in winds flowing out of a high-pressure center, and cyclonic or counterclockwise winds spiraling into a low-pressure area. In the Southern Hemisphere, winds and water movements shift in the opposite direction. The earth's rotation affects only large-scale movements, however. Contrary to popular beliefs, water draining out of a bathtub in the Southern Hemisphere is controlled by the shape of the drain, and will not necessarily swirl in the opposite direction from what it would in the north.

A major zone of subsidence occurs at about 30 north latitude. Air flows into this region of low pressure both from the north and south. Air flowing back toward the equator is turned toward the west by the Coriolis effect, creating the steady northeast "trade winds" of subtropical oceans. Their name comes from the dependable routes they provided for merchant sailing ships in earlier days. Where this dry, subsiding air falls on continents, it creates broad, subtropical desert regions (chapter 19). Air flowing north from this region of subsidence turns eastward, giving rise to the prevailing westerlies of middle latitudes. (Notice that an eastward flowing wind is called a west wind or a westerly, due to the direction from which it originates.)

Winds directly under regions of subsiding air often are light and variable. They create the so-called horse latitudes because sailing ships bringing livestock to the New World were often becalmed here and had to throw the bodies of dead horses overboard. Rising air at the equator creates doldrums where the winds may fail for weeks at a time. Another band of variable winds at about 60 north, called the polar front, tends to block the southward flow of cold polar air. As we will see in the next section, however, all these boundaries between major air flows wander back and forth, causing great instability in our weather patterns, especially in midcontinent areas. The Southern Hemisphere has more stable wind patterns because it has more ocean and less landmass than the Northern Hemisphere.

Jet Streams

Superimposed on the major circulation patterns and prevailing surface winds are variations caused by large-scale upper air flows and shifting movements of the large air masses that they push and pull. The most massive of these rivers of air are the jet streams, powerful winds that circulate in shifting flows rivaling the oceanic currents in extent and effect. Generally following meandering paths from west to east, jet streams can be as much as 50 km wide and 5 km deep. The number, flowing speed, location, and size of jet streams all vary from day to day and place to place.

Wind speeds at the center of a jet stream are often 200 km/hr (124 mph) and may reach twice that speed at times. Located 6 to 12 km (3.7-7.5 mi) above the earth's surface, jet streams follow discontinuities in the tropopause (the boundary between the troposphere and the stratosphere), where they are broken into large, overlapping plates that fit together like shingles on a roof. The jet streams are probably generated by strong temperature contrasts where adjacent plates overlap.

There are usually two main jet streams over the Northern Hemisphere. The subtropical jet stream generally follows a sinuous path about 30 north latitude (the southern edge of the United States), while the northern jet stream follows a more irregular path along the edge of a huge cold air mass called the circumpolar vortex (fig. 17.6) that covers the earth's top like a cap with scalloped edges. This whole polar vortex rotates from west to east slightly faster than the planet's rotation. As it moves, the lobes, or fingers, of cold air that protrude south from the vortex sweep across Canada and the United States. The clash between cold, dry arctic air masses pushing south against warm, wet air masses moving north from the Gulf of Mexico or the Pacific Ocean brings winds, rains, and storms to the middle of the continent.

During the winter, as the Northern Hemisphere tilts away from the sun and the atmosphere cools, the polar air masses become stronger and push further south, bringing snow and low temperatures across much of the United States. During the summer, as we tilt back toward the sun, warm air from the South pushes the polar jet stream back toward the pole.

Occasionally, the circumpolar vortex slows so that it rotates at nearly the same speed as the earth, stalling the motion of the lobes or air masses, and locking a huge ridge of hot, dry air over mid-America for months at a time. What causes airflow to be stalled like thisor to resume normal circulation patternsis unknown; but the amount of heat in the atmosphere surely plays a role.

Frontal Weather

The boundary between two air masses of different temperature and density is called a front. Fronts may be moving or stationary. When cooler air displaces warmer air, we call the moving boundary a cold front. Since cold air tends to be more dense than warm air, a cold front will hug the ground and push under warmer air as it advances. As warm air is forced upward, it cools adiabatically (without loss or gain of energy), and its cargo of water vapor condenses and precipitates. Upper layers of a moving cold air mass move faster than those in contact with the ground because of surface friction or drag, so the boundary profile assumes a curving, "bull-nose" appearance. Notice that the region of cloud formation and precipitation is relatively narrow. Cold fronts generate strong convective currents and often are accompanied by violent surface winds and destructive storms. An approaching cold front generates towering clouds called thunderheads that reach into the stratosphere where the jet stream pushes the cloud tops into a characteristic anvil shape. The weather after the cold front passes is usually clear, dry, and invigorating.

If the advancing air mass is warmer than local air, a warm front results. Since warm air is less dense than cool, air, an advancing warm front will slide up over cool, neighboring air parcels, creating a long, wedge-shaped profile with a broad band of clouds and precipitation. Gradual uplifting and cooling of air in the warm front avoids the violent updrafts and strong convection currents that accompany a cold front. A warm front will have many layers of clouds at different levels. The highest layers are often wispy cirrus (mare's tail) clouds that are composed mainly of ice crystals. They may extend 1,000 km (621 mi) ahead of the contact zone with the ground and appear as much as forty-eight hours before any precipitation. A moist warm front can bring days of drizzle and cloudy skies.

FRONT: The transition zone between two distinct airmasses. The basic frontal types are cold fronts, warm fronts and occluded fronts.

OCCLUDED FRONT: A complex frontal system that occurs when a cold front overtakes a warm front. Also known as an occlusion.

ANTICYCLONE: A large area of high pressure around which the winds blow clockwise in the Northern Hemisphere.

COLD FRONT: The boundary between a cold air mass that is advancing and a relatively warmer airmass. Generally characterized by steady precipitation followed by showery precipitation.

CYCLONE: An area of low pressure around which winds blow counterclockwise in the Northern Hemisphere. Also the term used for a hurricane in the Indian Ocean and in the Western Pacific Ocean.

HYGIENIC MEANING OF WEATHER IS COUSED BY ITS DIRECT AND INDIRECT INFLUENCE ON THE HUMAN ORGANISM.

Direct influence of the weather is called by warmness exchange of human. Indirect influence of the weather on the human organism is made by action of aperiodic changes of weather situation, that conflicts with common human rythms of physiologic functions (biorythms) and cause meteoneurologic conditions with disadaptic origin heliometeotropic (meteotropic) reactionsand diseases. Meteotropic reactions caused by changes of weather appears in healthy people, but in meteodepending people appears a weather-somatic syndrome (bad feeling, disorders of dreams, appearing of worry feeling, decreasing on capasity, fast feeling tired), meteotropic diseases appears in patients with chronic diseases of cardiovascular, respiratory or others systems, which become acuting by means of sharp weather changes.

The importance of determining the role of weather in human health cannot be understated. There are numerous other impacts of weather on the general health of the population, including morbidity, short-term changes in mood, emotional well-being, and aberratio ns from normal behavior. For example, asthma attacks, many of which occur from inhalation of airborne agents such as spores and molds, appear to be related to various meteorological variables. Goldstein (1980) found that clusters of attacks are preceded by the passage of a cold front followed by a high pressure system. Morbidity attributed to pneumonia, influenza, bronchitis, and probably many other illnesses is also weather-related.

Last year investigation has shown high adecvadity for medical foreseeing of weather and next profilactics of meteotropic reactions of weather classification.

Each of seven weather types has its own synoptic situation. Hygienic value of biotropness of each weather type is made with taking into account of intradayly meteoelements changing stage. There are five stages of weather changing: indiferent, weak, moderate, expressed, sharply expressed.

So hygienic value of impositve weather conditions, their medical interpritation play the main role inthe profilactics of heliometeotropic reactions, they allowed to indicate terms of profilactics of cardiovascular diseases, making of optimal microclimat of rooms, right choce of closes.

CLIMATE

The climate of an area, as previously noted, is the synthesis of the weather conditions that have prevailed there over a long period of time (usually 30 years). This synthesis involves both averages of the climatic elements and measurements of variability (such as extreme values and probabilities). Climate is a complex, abstract concept involving data on temperature, humidity, precipitation type and amount, wind speed and direction, atmospheric pressure, sunshine, cloud types and coverage, and such weather phenomena as fog, thunderstorms, and frost And the relationships among them. As such, no two localities on Earth may be said to have exactly the same climate. Nevertheless, it is readily apparent that, over restricted areas of the planet, climates vary within a limited range and that climatic regions are discernible within which some uniformity is apparent in the patterns of climatic elements. Moreover, widely separated areas of the world possess similar climates, which tend to recur in similar geographic relationships to each other. This symmetry and organization of the climatic environment suggests an underlying worldwide regularity and order in the phenomena causing climate (e.g.. patterns of radiation, atmospheric pressure, winds, fronts, and air masses), which were discussed in earlier sections.

http://www.cara.psu.edu/tools/health_climate/hc_extreme_events.asp

CLIMATES AND HEALTH

Human organism exists constantly interacting with the environment, one of the most important components of which is a climate. Tropic Hygiene is marked out as a special field of Hygiene owing to the fact, the climate of tropics has a great influence upon the hygienic life conditions and the conditions of human health.

The climate is a long-term weather regimen, corresponding to the geographical country and repeating appropriately.

Main climate-forming factors are: the latitude of the country and the intensity of solar irradiation, the appropriateness of atmospheric circulation, the type of land surface (dry land, relief, water and so on), the closeness of seas and oceans.

Climate-weather conditions have a direct or mediated influence upon people. The examples of direct influence are: the action of weather conditions upon human heat exchange, ultra-violet rays of solar radiation - upon the exchange of calcium. The latter is a very important thing for the prophylaxis of rickets.

Mediated action of climate is connected with the influence upon the character of human household and working activity, upon the pathological agents of infectious diseases and their carriers. The last fact conditions the geographical specificity of spread of different diseases. That's why regional climatic conditions must be taken into consideration during the working out of hygienic recommendations for the civil (living houses, hospitals) and industrial buildings, rational nourishment and way of life, for the choice of adequate clothes and footwear, work and rest regimen, prevention of diseases and education of the future generations. In his "Aphorisms" Hyppocratus said, that the diseases proceeded differently in different climatic conditions. He offered climate therapy for the treatment and health improvement, which was widely practiced at present.

Usually certain climate is spread over the large area about hundreds and even thousands kilometers. However, some regions of this large area can differ by their climate-weather conditions from other ones. That's why such a notion as microclimate was approved in climatology (the science about the Earth's climate). It means the features of physical condition of the near land layer above relatively small plot of land. So, we can speak about the microclimate of the wood, field, sea-coast, mountain slopes, oriented to the parts of the world differently, about the microclimate of vale, town, street and so on.

Now, many sciences adjoining to the climatology, are developed. Medical climatology studies the influence of climate-weather conditions upon the human organism and works out the methods of using climatic factors with the treatment and prophylactic aim. Medical geography studies the appropriateness of influence of climatic and social-economic conditions upon hygienic life conditions, health conditions and features of infectious and non-infectious diseases spread in different geographical regions. The materials of investigations are widely used in the working out and planning of corresponding programs and prophylaxis.

Most of people gradually adapt to every climate. The adaptation physiological reactions are based on reflexes, which are mobilized under the action of heat or cold. The development of human pathological conditions under the influence of hot tropical climate can be caused by some interconnected factors:

1) the disturbance of thermoregulation;

2) the disturbance of regulation of water-electrolyte balance;

3) the disturbance of cardio-vascular regulation.

Under the influence of heat, mainly physical and partially chemical phases of thermoregulation are activated. Heat emission increases and heat-production decreases. Both processes act at the same time. But in hot conditions the chemical thermoregulation isn't as powerful as the physical one.

In dry hot climate the evaporation proceeds easily. By 29 C heat emission increases from 12% to 70%. But, if the humidity grows on, the air cannot absorb water and heat. The thermoregulation becomes disturbed and the over-heating develops. In such conditions the air movement is very important for the comfort.

The acclimatization for the hot climate is a process of adaptation to the increased heat loads. It is shown as the lowering of muscular tone, the intensification of thermoregulation, the ability to make much sweat in proportion to heat load and to lower salt concentration in sweat, by the inadequate liquid intake.

It is found out that the acclimatization has some phases:

    Stage of alarm (the first hours in a new environment)

    Replacement of the old dynamic stereotype

    Incomplete acclimatization

    Complete acclimatization

Physiological changes can turn into pathological ones under certain conditions. Mental health has a great importance for the acclimatization.

Most of people, being in tropical countries, are able to acclimatize in 3 weeks. Some people with the good thermoregulatory abilities can acclimatize in 5-7 days. But there are some people very sensitive to the heat stress, who cannot acclimatize at all.

There are some clinical and experimental data, which are evidence of the advisability of human preliminary training to the action of high temperature to get quick acclimatization. It is realized by the daily staying in a heat chamber, where we can model different types of hot climate. Muscular work facilitates the adaptation to the hot.

The clothes, the formation of artificial microclimate (air conditioning) have a great importance for the organism protection from surplus heat and solar irradiation.

The breach of water-salt exchange under the influence of surplus heat is characterized by the next syndromes:

1)    hyposodiumaemia (the syndrome of salt insufficiency) and

2)    simple dehydration without salt loss.

In hot climate we usually meet dehydration, but sometimes we can observe both syndromes.

There is no one complete classification of heat exhaustion. Most of authors mark out the next basic forms:

Heat fever. Hyperpyrexia - is an acute overheating of the organism, caused by the disturbance of thermoregulation in hot climate, in hot period of the year, during stay in over-heated premises (hot shops). Usually it is observed in untrained newly arrived in tropics or hot countries. Under the influence of heat, their thermoregulatory system becomes exhausted. Hyperthermal diseases (malaria, tropical jungle), alcohol intoxication, vegetative dystony, etc have an influence upon the occurrence of heat hyperpyrexia.

The clinical course is variable. The symptoms of heat stroke occur during the maximum insolation and sometimes after the patient has come from the sun to the shade. If you bring the patient out of hyperthermal zone in prodromal period of the disease, help him quickly, the reaction is characterized by faint, feeling of closeness, weakness, a little increase of temperature, the dilation of pupils, dyspnoe.

In severe cases, the symptoms grow quickly. After the repeated faints with the dramatic adynamia, a severe headache, weakness in legs, tachycardia, sleepiness, sickness, frequent, superficial breathing, the squeezing in the chest develop. The skin is dry. Other symptoms are oliguria, photophobia, the hyperaemia of the face and conjunctives, narrow pupils. Salt insufficiency does not always occur. Then, we can observe a severe neurological condition: the increasing headache, excitement. Muscular fibrillations, epileptoid convulsions often occur. The breathing is superficial, frequent, and irregular. Body temperature increases up to 41-43 C. The patient loses consciousness, his pupils are dilated and don't react to the light, the pulse is faint, filiform, the peripheral blood supply is decreased. The skin is dry, hot or covered with sticky sweat. The face is pale, cyanotic. The defecation is irregular. Abdominal reflexes are lowered or absent. Usually we can reveal albuminuria. The shock develops

The prophylaxis. It is necessary to avoid the prolonged stay in the open sun with the uncovered head. The next measures are: rational work conditions, clothes, right water regimen, the training of acclimatization.

Heat exhaustion.

1) with mainly salt insufficiency.

The most considerable predisposing factors are abundant perspiration with the unrestored water and salt loss, gastro-intestinal disorders with vomiting and diarrhea. This type of heat exhaustion is usually met during hard physical work in hot conditions. The disturbance of water-salt balance (hyposodiumaemia) and vascular insufficiency occur in the first place.

The clinical course. The patient complains of headache, the absence of appetite, sickness, vomiting. Gradually, painful muscular spasms mainly in the muscles of calves and feet develop. It is typical of the patients with the repeated vomiting. Other symptoms are oliguria, vertigo, ataxia, and hallucinations. In severe cases the excitement, turning into the sharp inhibition of mental activity and even coma develop. We can observe the signs of organism dehydration, orthostatic unsteadiness, vascular insufficiency with the decrease of circulating blood volume, the increase of its viscosity, hematocrit, the number of RBC. In this case the condition could be accompanied by anuria and necrosis of renal canals. Chlorides concentration in urine is lowered. Hyposodiumaemia and hypochlorideaemia are found out in blood.

2) heat exhaustion with mainly water insufficiency.

Easy cases are met in the everyday life in tropics (when water loss isn't restored). The expressed forms occur seldom (for example, when the man stays in a desert for a long time). In mild cases the patient complains of headache, vertigo, weakness, oliguria, a little increase of body temperature. In severe cases, the complaints are: thirst, vascular collapses, difficult swallowing. The tongue and the mucous membranes of the oral cavity are dry. Body weight is decreased. Other symptoms are dyscoordination, coma quickly leading to death. Sometimes, the fit of hyperpyrexia precedes the death.

The prophylaxis. The regulation of water regimen should be followed during the whole hot season. Daily quantity of water is determined by the conditions of environment, the intensity of muscular work, the peculiarities of metabolism, the quantity and quality of food. The surplus and irregular drinking leads to the uneffective perspiration. It is recommended to use: 0.5% solution of sodium chloride, green tea, iced acidulated tea, mineral water, fizzy water. It is advisible to add some condensed milk to drinking water. Tomato juice with the table salt, raw fruits, water-melon, melon; grape-fruit, lemon, orange juice, tamarind juice, soft mineral drinks slake the thirst. The shower, bathing promote the prophylaxis of over-heating. It is necessary to avoid use alcohol and it is very important to follow the rules of personal hygiene and day regime.

CLIMATE CHANGE AND HEALTH

Climate influences many of the key determinants of health: temperature extremes and violent weather events; the geographical range of disease vectors; the quantity of air, food, and water; and the stability of the ecosystems which we depend on.

Because climate affects us in so many ways and because the details of how the global climate may change are so uncertain, prediction of the health effects of climate change is an inexact science at best. But given what is already known about the connection between climate and health and the magnitude of the global warming that scientists project, predict that future health effects can be substantial. These effects are likely to vary widely from region to region, because climate itself is predicted to change differently in various regions. For instance, temperatures are expected to rise more in some areas than others; some places will likely get drier, while others will get more rain than they do nowadays.

Health impacts of climate change include direct effects from temperature and weather extremes and from sea-level rise. A number of indirect impacts are also likely to arise from changes in precipitation and temperature patterns, which may disturb natural ecosystems, change the ecology of infectious diseases, harm agriculture and freshwater supplies, exacerbate air pollution levels, and cause large-scale reorganization of plant and animal communities. These indirect effects may, in the long run, have greater cumulative impacts on human health than the direct effects.

THE WEATHER AND CLIMATE HAVE A GREAT DIRECT AND INDIRECT INFLUENCE ON HUMAN BEINGS AND THEIR HEALTH.

Wetterklassen

Influence of the weather situation on the human organism. More information with the data sheet: Classes of weather:

Wetterklassen.pdf, 1.2 MB

Atmospheric conditions influence the growth and development of almost all life forms. Weather and climate also have an influence on man and his health. We can differentiate between direct and indirect meteorological influences.

 Direct influences

The most important direct influences are extreme weather situations, such as storms (hurricanes), extreme heat or cold, floods, drought or avalanches. All of these occurrences can endanger the health and even the lives of human beings. The damaging effects of too much UV radiation have also been proven. In particular, an increase in the incidence of skin cancer and eye cataracts has been established. Another of the direct influences is what we know as "meteorosensitivity". 30 to 50% of the population suffer under certain weather conditions. Well known in this respect are the influence of the Föhn wind, the Bise (a cold wind in Switzerland) and changes in the weather in general. The symptoms of meteorosensitivity are manifold. It is accepted that the weather can be an extra stress factor, as the human organism has to adapt to changing conditions in the atmosphere (changes in the weather).

 Indirect influences

Human health is indirectly influenced by pathogens, air pollution and allergies. Many transmitters of illnesses are dependent on meteorological conditions. The distribution of air pollutants is also closely related to meteorology. Air pollution
Weather and Health

can have a negative influence on people with respiratory diseases, such as asthma or chronic bronchitis. Allergies can be triggered by, amongst other things, pollen, fungal spores or dust mites.

 Positive influences

Although these negative influences exist, we must not forget the positive ones. For centuries we have known about the beneficial effects on our well-being of a stay at a health resort in the mountains or beside the sea. Meteorological elements such as sunshine, wind and certain temperature conditions stimulate the human organism. Also, a specific dose of UV radiation is vital for human health (it helps the body manufacture Vitamin D).

 Health and global warming

Because of increased concentrations of greenhouse gases in the atmosphere, we can count on a warmer climate. Changes in air temperature, air humidity, UV radiation and precipitation affect human health both directly and indirectly. For example, mild winters can reduce the number of deaths caused by the cold, whereas hot summer temperatures can increase the death rate. Pathogens are able to develop and spread more rapidly. This could mean that, in the future, malaria may crop up in areas where it is not to be found today. 

To characterize weather changeability they often use index of weather changeability:

, where

K - index of weather changeability

N number of days with contrast changes of weather

n number of days in studied period

If K is more than 30% - the weather regimen is changeable.

They use for predicting weather impacts on human health and for prevention of weather-related (meteotropic) diseases some medical classifications of weather. The most known are Fedorovs and Grigorievs classifications.

Classification of the weather by A. Fedorov

 

Temperature overfalls

Athmosperic pressure overfalls

Air movement velocity

Optimum

2oC

4 mb

2-3 m/s

Irritative

4oC

8 mb

6-7 m/s

Acute

>4oC

> 8 mb

>9 m/s

Acute weather is risky for heart attacks, strokes and developing complications of the chronic diseases. Irritative weather occurs exacerbations of chronic diseases and infectious diseases.

Classification of the weather by I. Grigoriev

 

Atmospheric pressure

Wind

Temperature overfalls

Pressure overfalls

Oxygen content

Very favorable

>760 mm Hg

0-3.0 m/s

-

0-5 mm Hg

315 mg/l and more

Favorable

755-760 mm Hg

4.0-7.0 m/s

1-5C

6-8 mm Hg

Need medical control

745-754 mm Hg

8.0-10.0 m/s

6-9C

9-14 mm Hg

289-260 mg/l

Need strict medical control

<745 mm Hg

Storm

>10C

>15 mm Hg

<260 mg/l

 

Medical classification of weather by I.I.Grygoriev (1974)

Types of weather

Characteristics of the weather

Very favorable

Constant weather which is mainly created by anticyclone, absence of noticeable cloudiness, rain. Atmospheric pressure is higher than 760 mm Hg, wind is 0-3,0 m/sec, pressure change is not more than 5 mm Hg, oxygen content is more than 315 mgm/l.

Favorable

Light changes of the weather of local character, short-time rain and changeable cloudiness. Atmospheric pressure is 760-755 mm Hg, wind is 4,0-7,0 m/sec, pressure change is 6-8 mm Hg, temperature change is not more than 5C, oxygen content is more than 315 mgm/l.

Weather that needs increased medical control

Cloudy, changeable weather, rain, often created by moderate cyclone, storms of local origin. Atmospheric pressure is 754-745 mm Hg, wind is 8,0-10,0 m/sec, pressure change is 9,0-14,0 mm Hg, temperature change is 6,0-9,0C, oxygen content is 260-289 mgm/l.

Weather that needs strict medical control

Weather is conditioned by deep cyclone, storms, intensive rain. Atmospheric pressure is lower than 745 mm Hg, pressure change is more than 14,0 mm Hg, temperature change is more than 10C. Oxygen content is 260 mgm/l.

 

 LEANING OF POPULATED PLACES

Disposal of Solid Wastes

Solid wastes include domestic refuse and other discarded solid materials, such as those from commercial, industrial, and agricultural operations; they contain increasing amounts of paper, cardboard, plastics, glass, and other packaging materials, but decreasing amounts of ash. The amounts produced are increasing throughout the world; urban wastes alone amount to about 600 kg per capita annually, and for industrialized countries probably at least 700 kg per capita, with an annual increase of 1-2 %. As the density of domestic waste is decreasing, annual per capita volumes of up to 5 cubic metres are common. These figures do not include the additional solid wastes produced by agricultural and industrial operations, and as a byproduct of sewage treatment.

The insanitary collection and disposal of solid wastes creates serious health hazards, e.g., by encouraging the breeding of flies, mosquitos, rodents, and other vectors of disease. It may also contribute to water pollution, air pollution, and soil pollution. It has adverse effects on land values, constitutes a public nuisance, and thus contributes to the deterioration of the environment.

The appropriate intervention and control measures are the rapid removal of refuse from premises by an efficient collection system and the proper processing of refuse before final disposal or re-use.

A refuse disposal system includes essentially: (1) the transportation system, using automotive vehicles, railway transport, pneumatic transport in pipelines under vacuum, and liquid transport in trunk sewers. Transfer stations for changing from one method of transport to another (e.g., truck hauling to railway hauling) are also necessary; (2) facilities for the processing of solid wastes, possibly using one or more of the following techniques: segregation of refuse components, incineration, composting, pulverization, compaction, and grinding; and (3) facilities for the sanitary discharge of residues into the environment, e.g., sanitary landfill, controlled discharge into bodies of water, and discharge into the air of combustion gases and particulate matter.

There are numerous alternatives for the handling and disposal of solid wastes. In selecting the best, consideration must first be given to the protection of the health of the community and the prevention of public nuisances. The salvaging of constituents of refuse, such as paper, glass, steel, etc., for re-use by industry must also be considered.

METHODS OF COLLECTION AND DISPOSAL

The rapid increase in the production of wastes is causing storage, collection, and transportation difficulties, as well as problems of treatment and final disposal.

Storage is largely a local problem; it becomes acute in housing developments and apartment blocks where adequate provision for storage has not been made. Collection and transportation have recently been intensively studied in various parts of the world, using operations research techniques, with a view to improving efficiency and lowering costs. Unconventional systems, such as hydraulic or pneumatic transport in pipes, are being developed, especially for new towns and residential areas. These developments, which are very promising, will eventually reduce collection costs and minimize human contact with solid wastes.

Collection and transportation costs vary widely, depending on population density, route planning, the location of disposal sites, labour costs, etc. Careful planning of routes and of pick-up procedures should make significant savings possible.

Substantial savings in handling costs can be achieved by conservation (reducing the volume of waste), land disposal and on-site treatment, both anaerobically or through the use of oxidation ponds or aeration ditches.

The most difficult problem, however, remains that of disposal. Because of the potential nuisance involved, the choice of disposal sites is often a source of serious" controversy. Ideally, the site should be selected or the basis of regional studies. The disposal methods of choice are incineration, sanitary landfill, and composting. Unfortunately, indiscriminate dumping is still practised, both on land and on sea. Incinerator design is improving as combustion efficiency improves and greater control is obtained over gaseous emissions; even after incineration, however, a sizeable volume of ash remains.

Composting, although it has widespread popular appeal, has become increasingly uneconomical as a means of disposal, both because of the changing nature of refuse and the difficulty in disposing of the compost itself.

Sanitary landfill is everywhere the most popular method of disposal. While it requires the use of relatively large areas, it can be used effectively for land reclamation purposes; when properly managed it can be inoffensive, and avoid both air pollution and, to a large extent, leaching and resulting water pollution. A modification of the process is being developed in certain areas; refuse is hauled relatively long distances by rail, and disposal is combined with strip-mining operations.

Other processes, still at the experimental stage, include pulverization into a dense, homogeneous, and relatively inoffensive material. This process reduces transport costs and land area requirements for sanitary landfill. Investigations are also being carried out on the high-pressure compaction of refuse into blocks of high density. These blocks could be used as a filling material and for the reclamation of derelict land.

The importance of recycling in refuse disposal has been emphasized by the conservation-minded. It is almost always a marginal operation from an economic point of view, although aluminium, glass, iron, paper, and other materials can be reclaimed.

TRANSPORT OF WASTEWATER

Wastewater is carried from its source to treatment facility pipe systems that are generally classified according to the type of wastewater flowing through them. If the system carries both domestic and storm-water sewage, it is called a combined system, and these usually serve the older sections of urban areas.

NATURE OF SEWAGE

The origin, composition, and quantity of waste are related to existing life patterns. When waste matter enters water, the resulting product is called sewage or wastewater.

Origin and Quantity

Wastewater originates mainly from domestic, industrial, groundwater, and meteorological sources, and these forms of wastewater are commonly referred to as domestic sewage, industrial waste, infiltration, and storm-water drainage, respectively.

Domestic sewage results from people's day-to-day activities, such as bathing, body elimination, food preparation, and recreation, averaging about 227 liters (about 60 gallons) per person daily. The quantity and character of industrial wastewater is highly varied, depending on the type of industry, the management of its water usage, and the degree of treatment the wastewater receives before it is discharged. A steel mill, for example, might discharge anywhere from 5700 to 151,000 liters (about 1500 to 40,000 gallons) per ton of steel manufactured. Less water is needed if recycling is practiced.

Infiltration occurs when sewer lines are placed below the water table or when rainfall percolates down to the depth of the pipe. It is undesirable because it imposes a greater load on the piping system and the treatment plant. The amount of storm-water drainage to be carried away depends on the amount of rainfall as well as on the runoff or yield of the watershed .

Composition

The composition of wastewater is analyzed using several physical, chemical, and biological measurements. The most common analyses include the measurements of solids, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and pH.

The solid wastes include dissolved and suspended solids. Dissolved solids are the materials that will pass through a filter paper, and suspended solids are those that do not (see Filtration). The suspended solids are further divided into settleable and nonsettleable solids, depending on how many milligrams of the solids will settle out of 1 liter of wastewater in 1 hour. All these classes of solids can be divided into volatile or fixed solids, the volatile solids generally being organic materials and the fixed solids being inorganic or mineral matter.

The composition of infiltration depends on the nature of the groundwater that seeps into the sewer. Storm-water sewage contains significant concentrations of bacteria, trace elements, oil, and organic chemicals.

Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from sewage. It includes physical, chemical and biological processes to remove physical, chemical and biological contaminants.

The site where the process is conducted is called a sewage treatment plant.

How is Wastewater Treated to Remove Pollutants?

Physics, Chemistry, Microbiology and Engineering are all involved in purifying wastewater so that it can be safely returned to the environment.

Wastewater treatment plants can be divided into two major types:
Biological and Physical/Chemical.

Biological plants are more commonly used to treat domestic or combined domestic and industrial wastewater from a municipality. They use basically the same processes that would occur naturally in the receiving water, but give them a place to happen under controlled conditions, so that the cleansing reactions are completed before the water is discharged into the environment.

Physical/chemical plants are more often used to treat industrial wastewaters directly, because they often contain pollutants which cannot be removed efficiently by microorganisms-- although industries that deal with biodegradable materials, such as food processing, dairies, breweries, and even paper, plastics and petrochemicals, may use biological treatment. And biological plants generally use some physical and chemical processes, too.

A physical process usually treats suspended, rather than dissolved pollutants. It may be a passive process, such as simply allowing suspended pollutants to settle out or float to the top naturally-- depending on whether they are more or less dense than water. Or the process may be aided mechanically, such as by gently stirring the water to cause more small particles to bump into each other and stick together, forming larger particles which will settle or rise faster-- a process known as flocculation. Chemical flocculants may also be added to produce larger particles. To aid flotation processes, dissolved air under pressure may be added to cause the formation of tiny bubbles which will attach to particles.

Filtration through a medium such as sand as a final treatment stage can result in a very clear water. Ultrafiltration, nanofiltration, and reverse osmosis are processes which force water through membranes and can remove colloidal material (very fine, electrically charged particles, which will not settle) and even some dissolved matter. Absorption (adsorption, technically) on activated charcoal is a physical process which can remove dissolved chemicals. Air or steam stripping can be used to remove pollutants that are gasses or low-boiling liquids from water, and the vapors which are removed in this way are also often passed through beds of activated charcoal to prevent air pollution. These last processes are used mostly in industrial treatment plants, though activated charcoal is common in municipal plants, as well, for odor control.

Some examples of chemical treatment processes, in an industrial setting, would be

    converting a dissolved metal into a solid, settleable form by precipitation with an alkaline material like sodium or calcium hydroxide. Dissolved iron or aluminum salts or organic coagulant aids like polyelectrolytes can be added to help flocculate and settle (or float) the precipitated metal.

    converting highly toxic cyanides used in mining and metal finishing industries into harmless carbon dioxide and nitrogen by oxidizing them with chlorine

    destroying organic chemicals by oxidizing them using ozone or hydrogen peroxide, either alone or in combination with catalysts (chemicals which speed up reactions) and/or ultraviolet light

In municipal treatment plants, chemical treatment-- in the form of aluminum or iron salts-- is often used for removal of phosphorus by precipitation. Chlorine or ozone (or ultraviolet light) may be used for disinfection, that is, killing harmful microorganisms before the final discharge of the wastewater. Sulfur dioxide or sulfite solutions can be used to neutralize (reduce) excess chlorine, which is toxic to aquatic life. Chemical coagulants are also used extensively in sludge treatment to thicken the solids and promote the removal of water.

A typical treatment plant consists of a train of individual unit processes set up in a series, with the output (effluent) of one process becoming the input (influent) of the next process. The first stages will usually be made up of physical processes that take out easily removable pollutants. After this, the remaining pollutants are generally treated further by biological or chemical processes. These may 1) convert dissolved or colloidal impurities into a solid or gaseous form, so that they can be removed physically, or 2) convert them into dissolved materials which remain in the water, but are not considered as undesirable as the original pollutants. The solids (residuals or sludges) which result from these processes form a side stream which also has to be treated for disposal.

A common set of processes that might be found at a municipal treatment plant would be:

    Preliminary treatment to remove large or hard solids that might clog or damage other equipment. These might include grinders (comminuters), bar screens, and grit channels. The first chops up rags and trash; the second simply catches large objects, which can be raked off; the third allows heavier materials, like sand and stones, to settle out, so that they will not cause abrasive wear on downstream equipment. Grit channels also remove larger food particles (i.e., garbage).

    Primary settling basins, where the water flows slowly for up to a few hours, to allow organic suspended matter to settle out or float to the surface. Most of this material has a density not much different from that of water, so it needs to be given enough time to separate. Settling tanks can be rectangular or circular. In either type, the tank needs to be designed with some type of scrapers at the bottom to collect the settled sludge and direct it to a pit from which it can be pumped for further treatment-- and skimmers at the surface, to collect the material that floats to the top (which is given the rather inglorious name of "scum".) The diagram below shows the operation of a typical primary settling tank.

    Secondary treatment, usually biological, tries to remove the remaining dissolved or colloidal organic matter. Generally, the biodegradation of the pollutants is allowed to take place in a location where plenty of air can be supplied to the microorganisms. This promotes formation of the less offensive, oxidized products. Engineers try to design the capacity of the treatment units so that enough of the impurities will be removed to prevent significant oxygen demand in the receiving water after discharge.

There are two major types of biological treatment processes: attached growth and suspended growth.

In an attached growth process, the microorganisms grow on a surface, such as rock or plastic. Examples are 1) open trickling filters, where the water is distributed over rocks and trickles down to underdrains, with air being supplied through vent pipes, 2) enclosed biotowers, which are similar, but more likely to use shaped, plastic media instead of rocks, and 3) so-called rotating biological contacters, or RBC's, which consist of large, partially submerged discs which rotate continuously, so that the microorganisms growing on the disc's surface are repeatedly being exposed alternately to the wastewater and to the air.

The most common type of suspended growth process is the so-called activated sludge system (see diagram below). This type of system consists of two parts, an aeration tank and a settling tank, or clarifier. The aeration tank contains a "sludge" which is what could be best described as a "mixed microbial culture", containing mostly bacteria, as well as protozoa, fungi, algae, etc. This sludge is constantly mixed and aerated either by compressed air bubblers located along the bottom, or by mechanical aerators on the surface. The wastewater to be treated enters the tank and mixes with the culture, which uses the organic compounds for growth-- producing more microorganisms-- and for respiration, which results mostly in the formation of carbon dioxide and water. The process can also be set up to provide biological removal of the nutrients nitrogen and phosphorus (see below).

After sufficient aeration time to reach the required level of treatment, the sludge is carried by the flow into the settling tank, or clarifier, which is often of the circular design. (An important condition for the success of this process is the formation of a type of culture which will flocculate naturally, producing a settling sludge and a reasonably clear upper, or supernatant layer. If the sludge does not behave this way, a lot of solids will be remain in the water leaving the clarifier, and the quality of the effluent wastewater will be poor.) The sludge collected at the bottom of the clarifier is then recycled to the aeration tank to consume more organic material. The term "activated" sludge is used, because by the time the sludge is returned to the aeration tank, the microorganisms have been in an environment depleted of "food" for some time, and are in a "hungry", or activated condition, eager to get busy biodegrading some more wastes. Since the amount of microorganisms, or biomass, increases as a result of this process, some must be removed on a regular basis for further treatment and disposal, adding to the solids produced in primary treatment.

Variations:
Sequencing Batch Reactor (SBR):The type of activated sludge system described above is a continuous flow process. There is a variation in which the entire activated sludge process take place in a single tank, but at different times. Steps include filling, aerating, settling, drawing off supernatant, etc. A system like this can provide more flexibility and control over the treatment, including nutrient removal, and is amenable to computer control.

Membrane Bioreactor (MBR): In this more recent innovation, treated water is pumped out of the aeration tank through banks of microfiltration membranes. Clarifiers are not needed. The sludge concentration can be higher than in a conventional system, which allows treatment in a smaller volume; and the sludge's ability to flocculate well is no longer a consideration. Low effluent solids concentrations can be achieved, which can helps in phosphorus removal and disinfection (see below). Click here for links to some commercial pages which discuss this process.

Nutrient removal refers to the treatment of the wastewater to take out nitrogen or phosphorus, which can cause nuisance growth of algae or weeds in the receiving water.

Nitrogen is found in domestic wastewater mostly in the form of ammonia and organic nitrogen. These can be converted to nitrate nitrogen by bacteria, if the plant is designed to provide enough oxygen and a long enough "sludge age" to develop these slow-growing types of organisms. The nitrate which is produced may be discharged; it is still usable as a plant nutrient, but it is much less toxic than ammonia. If more complete removal of nitrogen is required, a biological process can be set up which reduces the nitrate to nitrogen gas (and some nitrous oxide). There are also physical/chemical processes which can remove nitrogen, especially ammonia; they are not as economical for domestic wastewater, but might be suited for an industrial location where no other biological processes are in use. (These methods include alkaline air stripping, ion exchange, and "breakpoint" chlorination.)

Phosphorous removal is most commonly done by chemical precipitation with iron or aluminum compounds, such as ferric chloride or alum (aluminum sulfate). The solids which are produced can be settled along with other sludges, depending on where in the treatment train the process takes place. ("Lime", or calcium hydroxide, also works, but makes the water very alkaline, which has to be corrected, and produces more sludge.). There is also a biological process for phosphorus removal, which depends on designing an activated sludge system in such a way as to promote the development of certain types of bacteria which have the ability to accumulate excess phosphorus within their cells. These methods mainly convert dissolved phosphorus into particulate form. For treatment plants which are required to discharge only very low concentrations of total phosphorus, it is common to have a sand (or other type of) filter as a final stage, to remove most of the suspended solids which may contain phosphorus.

Disinfection, usually the final process before discharge, is the destruction of harmful (pathogenic) microorganisms, i.e. disease-causing germs. The object is not to kill every living microorganism in the water-- which would be sterilization-- but to reduce the number of harmful ones to levels appropriate for the intended use of the receiving water.

The most commonly used disinfectant is chlorine, which can be supplied in the form of a liquefied gas which has to be dissolved in water, or in the form of an alkaline solution called sodium hypochlorite, which is the same compound as common household chlorine bleach. Chlorine is quite effective against most bacteria, but a rather high dose is needed to kill viruses, protozoa, and other forms of pathogen. Chlorine has several problems associated with its use, among them 1) that it reacts with organic matter to form toxic and carcinogenic chlorinated organics, such as chloroform, 2) chlorine is very toxic to aquatic organisms in the receiving water-- the USEPA recommends no more than 0.011 parts per million (mg/L) and 3) it is hazardous to store and handle. Hypochlorite is safer, but still produces problems 1 and 2. Problem 2 can be dealt with by adding sulfur dioxide (liquefied gas) or sodium sulfite or bisulfite (solutions) to neutralize the chlorine. The products are nearly harmless chloride and sulfate ions. This may also help somewhat with problem 1.

A more powerful disinfectant is ozone, an unstable form of oxygen containing three atoms per molecule, rather than the two found in the ordinary oxygen gas which makes up about 21% of the atmosphere. Ozone is too unstable to store, and has to be made as it is used. It is produced by passing an electrical discharge through air, which is then bubbled through the water. While chlorine can be dosed at a high enough concentration so that some of it remains in the water for a considerable time, ozone is consumed very rapidly and leaves no residual. It may also produce some chemical byproducts, but probably not as harmful as those produced by chlorine.

The other commonly used method of disinfection is ultraviolet light. The water is passed through banks of cylindrical, quartz-jacketed fluorescent bulbs. Anything which can absorb the light, such as fouling or scale formation on the bulbs' surfaces, or suspended matter in the water, can interfere with the effectiveness of the disinfection. Some dissolved materials, such as iron and some organic compounds, can also absorb some of the light. Ultraviolet disinfection is becoming more popular because of the increasing complications associated with the use of chlorine.

We have purified and disinfected our wastewater and discharged a clean effluent into the receiving water. Now, what are we going to with all that sludge generated along the way?

Sludge from primary settling basins, called primary or "raw" sludge, is a noxious, smelly, gray-black, viscous liquid or semi-solid. It contains very high concentrations of bacteria and other microorganisms, many of them pathogenic, as well as large amounts of biodegradable organic material. Because of the high concentrations, any dissolved oxygen will be consumed rapidly, and the odorous and toxic products of anaerobic biodegradation (putrefaction) will be produced. The greasy floatable skimmings from primary treatment are another portion of this putrescible solid waste stream.

In addition to the primary sludge, wastewater plants with secondary treatment will produce a "secondary sludge", consisting largely of microorganisms which have grown as a result of consuming the organic wastes. While not quite so objectionable, due to the biodegradation which has already taken place, it is still very high in pathogens and contains much material which will decay and produce odors if not treated further.

Ultimately, the sludge must all be disposed of. The way in which this is done depends on the quality of the sludge-- and determines how it needs to be treated. The most desirable final fate for these solids would be for beneficial use in agriculture, since the material has organic matter to act as a soil conditioner, as well as a some fertilizer value. This requires the highest quality "biosolids", free of contamination with toxic metals or industrial organic compounds, and low in pathogens. At a somewhat lower quality, it can be used for similar purposes on non-agricultural land and for land reclamation (e.g., strip mines). Poorer quality sludge can be disposed of by landfilling or incineration.

One commonly used method of sludge treatment, called digestion, is biological. Since the material is loaded with bacteria and organic matter; why not let the bacteria eat the biodegradable material? Digestion can be either aerobic or anaerobic. Aerobic digestion requires supplying oxygen to the sludge; it is similar to the activated sludge process, except no external "food" is provided. In anaerobic digestion, the sludge is fed into an air-free vessel; the digestion produces a gas which is mostly a mixture of methane and carbon dioxide. The gas has a fuel value, and can be burned to provide heat to the digester tank and even to run electric generators. Some localities have compressed the gas and used it to power vehicles. Digestion can reduce the amount of organic matter by about 30 to 70 percent, greatly decrease the number of pathogens, and produce a liquid with an inoffensive, "earthy" odor. This makes the sludge safer to dispose of on land, since the odor does not attract as many scavenging pests, such as flies, rodents, gulls, etc., which spread pathogens from the disposal site to other areas-- and there are fewer pathogens to be spread.

A liquid sludge, which might contain 3 to 6% dry weight of solids, can be dewatered to form a drier sludge cake of maybe 15 to 25 percent solids, which can be hauled as a solid rather than having to be handled as a liquid. Equipment used to dewater sludge includes centrifuges, vacuum filters, and belt presses or plate-and-frame presses. Chemical coagulants are commonly added to help form larger aggregates of solids and release the water.

Click here to see an animation of a belt filter press in action.

Further processes such as composting and heat drying can produce a drier product with lower pathogen levels. Another approach involves treatment with lime (calcium oxide), which kills pathogens due to its highly alkaline nature as well as the heat that is generated as it reacts with the water in the sludge; this also results in a drier product. A final disposal method which eliminates all of the pathogens and greatly reduces the volume of the sludge is incineration. This is not considered a beneficial use, however, and is becoming less popular due to public concerns over air emissions.

Sludges from physical-chemical treatment of industrial waste streams containing heavy metals and non-biodegradable toxic organic compounds often must be handled as hazardous wastes. Some of these will end up in hazardous waste landfills, or may be chemically treated for detoxification-- or even for recovery of some components for recycling. Recalcitrant organic compounds can be destroyed by carefully controlled high-temperature incineration, or by other innovative processes, such as high-temperature hydrogen reduction.

In the handling and treatment of both wastewater and sludge, a prime concern is odor control.

In the sewers, prevention of anaerobic conditions and sulfide formation is an important consideration in preventing odors. Hydrogen sulfide is also the major cause of sewer corrosion. If the water is warm and the flow is not rapid enough to aerate the water and scour the pipes, addition of chemicals such as nitrate, hydrogen peroxide or iron compounds can be helpful. In processes where odors are inevitable, the areas must be contained and ventilated. The air then has to be passed through some type of treatment system, such as an activated charcoal bed, a chemical scrubber (often using hypochlorite solution), a compost pile type biofilter-- or the air can even be used as part of the air supply for an activated sludge system.

I have tried, on this page, to introduce the basics of wastewater treatment. There are many variations and different combinations of treatment processes, as well as innovative methods not discussed here. I have focused on conventional treatment processes, which tend to be built in concrete structures and use a lot of energy-consuming machinery, with the goal of eliminating pollutants. There has been considerable interest, recently, in more "low-tech", environmentally friendly, wastewater treatment processes which consume less energy and allow for recycling of more of the nutrients. My links page contains some information about some of these alternative treatment methods. Some companies involved in the production of phosphates for fertilizer use are even interested in recovering these compounds from wastewater to supplement the supply of mined phosphate rock. Water pollution control is a field in which much process research and engineering development is continuing to taking place.

 

WASTEWATER TREATMENT

The processes involved in municipal wastewater treatment plants are usually classified as being part of primary, secondary, or tertiary treatment.

A Primary Treatment

The wastewater that enters a treatment plant contains debris that might clog or damage the pumps and machinery. Such materials are removed by screens or vertical bars, and the debris is burned or buried after manual or mechanical removal. The wastewater then passes through a comminutor (grinder), where leaves and other organic materials are reduced in size for efficient treatment and removal later.

 

1 Grit Chamber

In the past, long and narrow channel-shaped settling tanks, known as grit chambers, were used to remove inorganic or mineral matter such as sand, silt, gravel, and cinders. These chambers were designed to permit inorganic particles 0.2 mm (0.008 in) or larger to settle at the bottom while the smaller particles and most of the organic solids that remain in suspension pass through. Today, spiral-flow aerated grit chambers with hopper bottoms, or clarifiers with mechanical scrapper arms, are most commonly used. The grit is removed and disposed of as sanitary landfill. Grit accumulation can range from 0.08 to 0.23 cu m (3 to 8 cu ft) per 3.8 million liters (about 1 million gallons) of wastewater.

2 Sedimentation

With grit removed, the wastewater passes into a sedimentation tank, in which organic materials settle out and are drawn off for disposal. The process of sedimentation can remove about 20 to 40 percent of the BOD5 and 40 to 60 percent of the suspended solids.

The rate of sedimentation is increased in some industrial waste-treatment stations by incorporating processes called chemical coagulation and flocculation in the sedimentation tank. Coagulation is the process of adding chemicals such as aluminum sulfate, ferric chloride, or polyelectrolytes to the wastewater; this causes the surface characteristics of the suspended solids to be altered so that they attach to one another and precipitate. Flocculation causes the suspended solids to coalesce. Coagulation and flocculation can remove more than 80 percent of suspended solids.

3 Flotation

An alternative to sedimentation that is used in the treatment of some wastewaters is flotation, in which air is forced into the wastewater under pressures of 1.75 to 3.5 kg per sq cm (25 to 50 lb per sq in). The wastewater, supersaturated with air, is then discharged into an open tank; there the rising air bubbles cause the suspended solids to rise to the surface, where they are removed. Flotation can remove more than 75 percent of the suspended solids.

4 Digestion

Digestion is a microbiological process that converts the chemically complex organic sludge to methane, carbon dioxide, and an inoffensive humuslike material. The reactions occur in a closed tank or digester that is anaerobicthat is, devoid of oxygen. The conversion takes place through a series of reactions. First the solid matter is made soluble by enzymes, then the substance is fermented by a group of acid-producing bacteria, reducing it to simple organic acids such as acetic acid. The organic acids are then converted to methane and carbon dioxide by bacteria. Thickened sludge is heated and added as continuously as possible to the digester, where it remains for 10 to 30 days and is decomposed. Digestion reduces organic matter by 45 to 60 percent.

5 Drying

Digested sludge is placed on sand beds for air drying. Percolation into the sand and evaporation are the chief processes involved in the dewatering process. Air drying requires dry, relatively warm weather for greatest efficiency, and some plants have a greenhouselike structure to shelter the sand beds. Dried sludge in most cases is used as a soil conditioner; sometimes it is used as a fertilizer because of its 2 percent nitrogen and 1 percent phosphorus content.

B Secondary Treatment

Having removed 40 to 60 percent of the suspended solids and 20 to 40 percent of the BOD5 in primary treatment by physical means, the secondary treatment biologically reduces the organic material that remains in the liquid stream. Usually the microbial processes employed are aerobicthat is, the organisms function in the presence of dissolved oxygen. Secondary treatment actually involves harnessing and accelerating nature's process of waste disposal. Aerobic bacteria in the presence of oxygen convert organic matter to stable forms such as carbon dioxide, water, nitrates, and phosphates, as well as other organic materials. The production of new organic matter is an indirect result of biological treatment processes, and this matter must be removed before the wastewater is discharged into the receiving stream.

Secondary Sedimentation tank at a rural treatment plant

Several alternative processes are also available in secondary treatment, including a trickling filter, activated sludge, and lagoons.

1 Trickling Filter

In this process, a waste stream is distributed intermittently over a bed or column of some type of porous medium. A gelatinous film of microorganisms coats the medium and functions as the removal agent. The organic matter in the waste stream is absorbed by the microbial film and converted to carbon dioxide and water. The trickling-filter process, when preceded by sedimentation, can remove about 85 percent of the BOD5 entering the plant.

Trickling filter bed using plastic media

B2 Activated Sludge

This is an aerobic process in which gelatinous sludge particles are suspended in an aeration tank and supplied with oxygen. The activated-sludge particles, known as floc, are composed of millions of actively growing bacteria bound together by a gelatinous slime. Organic matter is absorbed by the floc and converted to aerobic products. The reduction of BOD5 fluctuates between 60 and 85 percent.

An important companion unit in any plant using activated sludge or a trickling filter is the secondary clarifier, which separates bacteria from the liquid stream before discharge.

3 Stabilization Pond or Lagoon

Another form of biological treatment is the stabilization pond or lagoon, which requires a large land area and thus is usually located in rural areas. Facultative lagoons, or those that function in mixed conditions, are the most common, being 0.6 to 1.5 m (2 to 5 ft) in depth, with a surface area of several acres. Anaerobic conditions prevail in the bottom region, where the solids are decomposed; the region near the surface is aerobic, allowing the oxidation of dissolved and colloidal organic matter. A reduction in BOD5 of 75 to 85 percent can be attained.

 

 C Advanced Wastewater Treatment

If the receiving body of water requires a higher degree of treatment than the secondary process can provide, or if the final effluent is intended for reuse, advanced wastewater treatment is necessary. The term tertiary treatment is often used as a synonym for advanced treatment, but the two methods are not exactly the same. Tertiary, or third-stage, treatment is generally used to remove phosphorus, while advanced treatment might include additional steps to improve effluent quality by removing refractory pollutants. Processes are available to remove more than 99 percent of the suspended solids and BOD5. Dissolved solids are reduced by processes such as reverse osmosis and electrodialysis. Ammonia stripping, denitrification, and phosphate precipitation can remove nutrients. If the wastewater is to be reused, disinfection by ozone treatment is considered the most reliable method other than breakpoint chlorination. Application of these and other advanced waste-treatment methods is likely to become widespread in the future in view of new efforts to conserve water through reuse.

D Liquid Disposal

The ultimate disposal of the treated liquid stream is accomplished in several ways. Direct discharge into a receiving stream or lake is the most commonly practiced means of disposal. The treatment process involves conventional primary and secondary treatment followed by lime clarification to remove suspended organic compounds. During this process, an alkaline (high-pH) condition is created to improve the process. In the next step, recarbonation is used to bring the pH level to neutral. Then the water is filtered through multiple layers of sand and charcoal, and ammonia is removed by ionization. Pesticides and any other dissolved organic materials still present are absorbed by a granular, activated-carbon filter. Viruses and bacteria are then killed by ozonization. At this stage the water should be cleansed of all contaminants, but, for added reliability, second-stage carbon adsorption and reverse osmosis are used, and chlorine dioxide is added to attain the highest possible water standard.

E Septic Tank

A sewage treatment process commonly used to treat domestic wastes is the septic tank: a concrete, cinder block or metal tank where the solids settle and the floatable materials rise. The partly clarified liquid stream flows from a submerged outlet into subsurface rock-filled trenches through which the wastewater can flow and percolate into the soil where it is oxidized aerobically. The floating matter and settled solids can be held from six months to several years, during which they are decomposed anaerobically.

 

1 Grate

2 Grit chamber

3 Pipe to remove sand from Grit chamber

4 The compressor station for air supply in aeration tank

5 Sludge drying bed

6 Primary treatment

7 The process of water entering into aeration tank from primary treatment

9 Aeration tank

10 The process of water entering into Secondary treatment

11 Metatank for activation of sludge

12 Secondary treatment

13 Chlorine contakt tank

14 Chlorinator

15 Discharge effluent to lake, stream

Living with the Weather - Effects

Weather and our Physical Health

WEATHER AND OUR PHYSICAL HEALTH

It is true that we can be 'under the weather'. Weather has short and long term effects on our bodies and this is studied by scientists called bio meteorologists. It affects the death rate and is linked to seasonal illnesses such as winter flu, sunstroke, or hay fever. Some people claim that they can feel changes in the weather with aches and pains worsening and the onset of headaches. Some sufferers of rheumatism or arthritis even notice changes in atmospheric pressure affecting the fluid around their joints.

Our bodies react differently to the weather depending on our age, sex, or general state of health as well as where we actually live. These reactions are linked to our endocrine system, the system of glands which regulates the production of hormones in our bodies, and which is affected by pain, stress and the weather. One in three people are thought to be sensitive to the changing weather but the old, young and the chronically ill suffer more, and women are generally more sensitive than men.

How Weather affects us

To protect itself from too much heat or cold the body sweats or shivers. When we sweat, perspiration evaporates from the skin and cools you down. When we shiver muscles twitch and give off heat. In extreme heat our heart rate rises, blood vessels expand to let more blood reach the skin's surface (blushing helps us to cool down) and we sweat more. This can cause fainting, sunstroke and rashes, but the combination of dehydration and loss of blood from the central nervous system can lead to collapse. Elderly people are most affected by the heat but many young men drown each year trying to cool off with a swim or a paddle. The contrast between a high body temperature and the cold water can cause cramp especially if people swim after eating or drinking. In extreme cold our bodies react by closing blood vessels to keep the blood away from the skin and retain heat. However, for old people with poor circulation this can lead to a cycle of falling body temperature, inactivity, a further fall in body temperature and eventually death. Every winter the death rate rises because of this hypothermia, but other illnesses such as winter colds and flu can develop into pneumonia and bronchitis which can be very dangerous for those who are fragile. See weather dangers for more about the affects of extreme heat and cold.

Hayfever is an allergy to airborne pollen grains and it is at its worst during the early summer - exam period for schoolchildren and students who often rely on anti-histamine drugs to help them manage its ill-effects such as itchy eyes and dripping nose. Air pollution especially affects people with chronic lung diseases such as asthma and bronchitis. The famous London smogs killed thousands of people when smoke from factories and house fires converted ordinary fog into lethal smog. These only stopped after the Clean Air Act of 1956 which outlawed smoke from coal fired chimneys. Today a new form of smog caused mainly by traffic exhaust emissions is giving us problems with air quality in some areas. You can look up a Pollution Index and a Pollen Index on this site.

The ultra violet (UV) rays of the sun can cause the skin to burn if unprotected. Habitual sun-worshippers are most at risk, but even a single over-exposure to UV rays can permanently damage the skin. Fair-skinned people tend to get sunburnt more easily than people with darker skin which contains a lot of melanin, a brown pigment which acts as a shield against the harmful rays. There has been a dramatic increase in skin cancers, with cases of the most lethal, melanoma, doubling every ten years. Now that we are aware of the link between sun damage and skin cancers we can protect ourselves by using sunscreen creams. However we also have to be aware that the effect of the sun's rays increases according to the height and strength of the sun and in some parts of the world the ozone layer has been partially depleted allowing more of the harmful UV rays to get through. The Sun Index measures this and can be found on this site.

Sunshine is good for us in small quantities and is needed by our bodies to make vitamin D which is important for healthy growth. Too little sunshine can cause rickets which occurs when a lack of vitamin D prevents the bones growing properly. This was common in Victorian times but has been virtually eradicated in the UK because of healthier diets and greater exposure to sunlight.

Different weather has benefits for health, and climatotherapy is the idea of recommending different weather conditions for different illnesses. Patients with tuberculosis or blood diseases were often sent to mountain resorts with their lower levels of water vapour and higher ozone levels. Seaside resorts were considered to be good for the health with the sea air being rich in sodium and iodine vital for the healthy functioning of the body. The seaside climate is also recommended for those suffering from such chronic illnesses as bronchitis and rheumatism. In some cases we create an artifical environment by using ionisers, air conditioning or humidifiers. This can be bad for the health too and bad air conditioning systems have been blamed for Sick Building Syndrome in which increased concentrations of germs, bacteria and other pollutants like cigarette smoke cause a wide variety of health complaints.

http://www.bbc.co.uk/weather/weatherwise/living/effects/morale.shtml

Our morale is affected by weather

Weather and our Psychological Health

Bio meteorologists have noted that our morale and state of mind can be affected by changes in the weather. In particular, heat waves have been seen to affect tiredness, headaches, insomnia, bad temper and forgetfulness. It is harder to work productively in over-heated environments, and incidents of road rage and accidents increase when the mercury rises. In hot weather the body produces chemicals which impair judgement and reduce concentration. Adding in the traffic jams during holiday periods and the mechanical problems that increase, it is probably better to stay off the road altogether.

Weather and Depression

Serious mental conditions such as schizophrenia and manic depression are said to worsen with changes in the weather, and suicide rates are affected too. Hot weather is also linked with higher levels of street violence and attacks, as well as rioting and unrest. The hot dry Fohn and Scirocco winds are said to damage the health - in Germany the accident, crime and suicide rates rise during the Fohn, whilst the Scirocco is said to cause madness.

Winter weather brings us a condition known as Seasonal Affective Disorder or SAD. This is a type of clinical depression linked with the lack of sunlight during the winter months. It causes lethargy, sadness, loss of appetite and disturbed sleep but it is still argued by some that this is just a bout of mid-winter blues rather than an actual illness. It has been treated successfully in many cases by exposing patients to strong artificial daylight and some people buy special 'daylight' bulbs for their house plants and themselves!

10 Weather Phobias

   Brontophobia - Fear of thunder

   Astrapophobia - Fear of lightning

   Anemophobia - Fear of wind

   Chionophobia - Fear of snow

   Cryophobia - Fear of ice and frost

   Heliophobia - Fear of the Sun and light

   Homichlophobia - Fear of fog

   Nephelophobia - Fear of clouds

   Ombrophobia - Fear of rain

   Psychrophobia - Fear of cold

http://www.bbc.co.uk/weather/weatherwise/living/influence/

REFERENCES:

Principal:

1.          Hygiene and human ecology. Manual for the students of higher medical institutions/ Under the general editorship of V.G. Bardov. K., 2009.  PP. 14-34, 71-106.

2.          Datsenko I.I., Gabovich R.D .Preventive medicine. - K.: Health, 2004, pp. 14-74.

3.          Lecture on hygiene.

Additional:

1.          Kozak D.V., Sopel O.N., Lototska O.V. General Hygiene and Ecology. Ternopil: TSMU, 2008. 248 p.

2.          Dacenko I.I., Denisuk O.B., Doloshickiy S.L. General hygiene: Manual for practical studies. -Lviv: Svit, 2001. - P. 6-23.

3.          A hand book of Preventive and Social Medicine. Yash Pal Bedi / Sixteenth Edition, 2003   p. 26-36, 92-97.