METHODOLOGY FOR ENVIRONMENTAL ASSESSMENT ON CHEMICAL AND PHARMACEUTICAL COMPANIES.
METHODS OF ENVIRONMENTAL POLLUTION FROM ENERGY (NOISE, VIBRATION, ELECTROMAGNETIC FIELDS, IONIZING RADIATION).
Air pollution is the introduction into the atmosphere of chemicals, particulates, or biological materials that cause discomfort, disease, or death to humans, damage other living organisms such as food crops, or damage the natural environment or built environment.
The atmosphere is a complex dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
Schematic drawing, causes and effects of air pollution: greenhouse effect, particulate contamination, increased UV radiation, acid rain, increased ground level ozone concentration, increased levels of nitrogen oxides.
A substance in the air that can be harmful to humans and the environment is known as an air pollutant. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made. Pollutants can be classified as primary or secondary. Usually, primary pollutants are directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulphur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone — one of the many secondary pollutants that make up photochemical smog. Some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.
Major primary pollutants produced by human activity include:
Secondary pollutants include:
Minor air pollutants include:
Persistent organic pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulate in human and animal tissue, biomagnify in food chains, and to have potential significant impacts on human health and the environment.
Sources of air pollution refer to the various locations, activities or factors which are responsible for the releasing of pollutants into the atmosphere. These sources can be classified into two major categories which are:
Anthropogenic sources (human activity) mostly related to burning different kinds of fuel
Main article: AP 42 Compilation of Air Pollutant Emission Factors
Industrial air pollution emissions
Air pollutant emission factors are representative values that people attempt to relate the quantity of a pollutant released to the ambient air with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate emitted per tonne of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available data of acceptable quality, and are generally assumed to be representative of long-term averages.
There are 12 compounds in the list of POPs. Dioxins and furans are two of them and are intentionally created by combustion of organics, like open burning of plastics. The POPs are also endocrine disruptor and can mutate the human genes.
The United States Environmental Protection Agency has published a compilation of air pollutant emission factors for a multitude of industrial sources. The United Kingdom, Australia, Canada and many other countries have published similar compilations, as well as the European Environment Agency.
Noise pollution: non-auditory effects on health
Noise is a prominent feature of the environment including noise from transport, industry and neighbours. Exposure to transport noise disturbs sleep in the laboratory, but not generally in field studies where adaptation occurs. Noise interferes in complex task performance, modifies social behaviour and causes annoyance. Studies of occupational and environmental noise exposure suggest an association with hypertension, whereas community studies show only weak relationships between noise and cardiovascular disease. Aircraft and road traffic noise exposure are associated with psychological symptoms but not with clinically defined psychiatric disorder. In both industrial studies and community studies, noise exposure is related to raised catecholamine secretion. In children, chronic aircraft noise exposure impairs reading comprehension and long-term memory and may be associated with raised blood pressure. Further research is needed examining coping strategies and the possible health consequences of adaptation to noise.
Noise Control & Vibration Assessment Services
Acoustics is the science that deals with the study and technology of sound. Generally the study of acoustics includes the generation, propagation, control and reception of mechanical waves and vibrations, their interaction with materials and their effects.
Noise is sometimes defined as unwanted or excessive sound. Depending upon the circumstances - noise can give rise to nuisance and disturbance (environmental or community noise). Occupational exposure to noise (workplace noise) can cause noise induced hearing loss (NIHL) and tinnitus. Excessive noise at work has also been identified as a potential factor in workplace accidents.
When a surface or structure rapidly oscillates backwards or forwards the motion is referred to as vibration. The rate at which the occillation (repeated movement) occurs is known as the frequency of the vibration and this is measured in cycles per second or hertz (Hz). Sound and vibration are closely related and sound can be considered as pressure waves or air vibrations which are audible. These waves are generated by vibrating structures (e.g., loudspeakers or human vocal cords) and these pressure waves can also induce the vibration of structures. Many activities (e.g., heavy traffic, quarry blasts, etc.) have the potential to give rise to sound and vibration emissions.
Vibration within buildings is generally assessed in terms of its acceptability to the human occupants. In most instances there is a need to distinguish between the perceived risk and the actual risk and invariability we assess the level of vibration against specified criteria. Occasionally large amplitude shock and vibrations will need to be assessed with respect to their potential effects on the buildings and structures, as opposed to the building occupants.
The mechanisms and standards for controlling and regulating noise depend on the nature of the source, e.g., road traffic noise is controlled and assessed quite differently to factory noise or noise from a night club. Equally, construction noise, recreational noise and ‘neighbour noise’ may need to be assessed using different criteria and standards. Throughout industry, noise control measures are often required to protect the hearing of workers. On the other hand, environmental noise control generally gives priority to protecting Noise Sensitive Locations (NSLs) or noise sensitive receptors.
A range of factors (acoustic and non-acoustic) will affect the tolerance and or reaction of an individual to noise and the overall impact of a noise source. In assessing the likelihood of environmental noise complaints BS 4142 (1997) gives priority to the degree by which the noise exceeds the pre-existing noise levels. Some of the other pertinent factors in assessing or predicting noise impacts or nuisance complaints include:
• The absolute
sound pressure level of the noise source and variations over time
• Frequency of the noise (spectral components)
• Extent of the impulsive elements and special features or characteristics of the noise
• Variations in the hearing sensitivity of individuals
• Site location and local land use
• Nature and character of the locality
• Activities underway when noise is audible
• Local attitudes to the source or sources of the noise
• The likely duration of the noise and the ability and/or willingness to control its impact.
The above list is by no means exhaustive and many social, psychological and economic factors will affect the sensitivity of an individual or a situation over time.
At some facilities the nature of the activities or the proximity of of NSLs may result in potential noise problems. In such cases, the key environmental noise issues (dominant sources, noisy production processes etc. and their impact on noise sensitive locations) need to be identified. At such facilities it is important to adopt a logical and systematic approach to noise management.
At some sites a combination of factors (e.g. inherently quiet plant, effective containment of noisy sources or remoteness of NSLs) ensures that environmental noise is a minor issue and significant noise impacts are unlikely to arise. However, some plants will require an ongoing programme of work to ensure an effective level of control over the facility’s noise emissions. In some instances this is best achieved through a structured Noise Management Programme (or Noise Management Plan) based on a risk assessment approach.
The first step generally involves an assessment of any existing or planned noise sources and their relative contribution to ambient levels. This facilitates the establishment of target noise levels for the particular source and where necessary the degree of noise attenuation can be estimated. Having established the required reduction, the next stage is the application of noise control engineering principles. However, effective planning and management frequently involves the use of common sense and good practice as opposed to high tech engineering solutions.
Virtually all noise control problems can be represented by a simple energy flow diagram. This generally gives rise to two main options of control, i.e. to reduce the source strength or to impede the acoustic energy along its transmission path. In every situation the mechanisms by which a sound is generated and the exact part of the machinery/equipment responsible will largely dictate the treatment options.
With the exception of aerodynamic noise, noise is generally caused by a force causing a surface to vibrate. Surfaces or panels radiate sound most efficiently at or near any of their modal or resonant frequencies and some control measures involve the application of coatings or damping layers or mechanical stiffening devices which subdivide the panel so that the modal frequencies move upwards and become less problematical.
While noise control engineering is a specialist subject, in many situations the objective is to decouple the mechanical path between the source of vibration and the radiating surface. There are a wide range of noise control techniques, however, they can be loosely categorised as follows:
· controlling resonance – e.g. altering the mass and/or stiffness of the panel or changing a machine’s running speed to detune it from the natural frequency of the panel;
· control of stiffness – e.g. the use of resilient layers/treatments and the addition of coupling devices;
· vibration isolation – e.g. the use of isolating springs to reduce the transmission of vibration to building structures or to larger machines or machine parts; and
· increase in damping – i.e., a process whereby vibrational energy is converted into heat through some form of frictional mechanism (e.g. constrained or unconstrained layer damping techniques).
Many noise sources such as industrial machinery have a fixed design which may be difficult to modify without reducing its performance or efficiency, however, noise is frequently caused by the turbulent flow of gases and fluids and these types of noise sources can be modified to reduce their noise output. Common examples of these include exhausts and blow-offs of air or steam which cause jet noise. Other common examples include turbulence caused by control valves in pipelines. In most systems the noise emission is directly proportional to the degree of turbulence and many control techniques aim to reduce the velocity and pressure of the fluids and smooth out the flow.
Predictive maintenance techniques help us to determine and evaluate the condition of plant and equipment in order to predict when specific maintenance tasks should be performed. This approach can help to optimise resources and provide significant cost savings over routine/time-based maintenance. The use of vibro-acoustical analysis and diagnostic systems enable Moloney & Associates Acoustic & Environmental Consultants, Cork to utilize advanced technology and condition/diagnostic monitoring methods to assist clients. These methods and technologies can be effectively applied to any sector or industry where rotating machinery is used.
Table of Contents
1. Pollution (definition)
2. Water Pollution
3. Thermal Pollution
4. Land Pollution
5. Pestiside Pollution
6. Radiation Pollution
7. Noise Pollution
8. Air Pollution
Pollution - Environmental pollution is any discharge of material or energy into water, land, or air that causes or may cause acute (short-term) or chronic (long-term) detriment to the Earth's ecological balance or that lowers the quality of life. Pollutants may cause primary damage, with direct identifiable impact on the environment, or secondary damage in the form of minor perturbations in the delicate balance of the biological food web that are detectable only over long time periods.
Until relatively recently in humanity's history, where pollution has existed, it has been primarily a local problem. The industrialization of society, the introduction of motorized vehicles, and the explosion of the human population, however, have caused an exponential growth in the production of goods and services. Coupled with this growth has been a tremendous increase in waste by-products. The indiscriminate discharge of untreated industrial and domestic wastes into waterways, the spewing of thousands of tons of particulates and airborne gases into the atmosphere, the "throwaway" attitude toward solid wastes, and the use of newly developed chemicals without considering potential consequences have resulted in major environmental disasters, including the formation of smog in the Los Angeles area since the late 1940s and the pollution of large areas of the Mediterranean Sea. Technology has begun to solve some pollution problems (see pollution control), and public awareness of the extent of pollution will eventually force governments to undertake more effective environmental planning and adopt more effective antipollution measures.
Different Types of Pollution
Water pollution is the introduction into fresh or ocean waters of chemical, physical, or biological material that degrades the quality of the water and affects the organisms living in it. This process ranges from simple addition of dissolved or suspended solids to discharge of the most insidious and persistent toxic pollutants (such as pesticides, heavy metals, and nondegradable, bioaccumulative, chemical compounds).
Conventional or classical pollutants are generally associated with the direct input of (mainly human) waste products. Rapid urbanization and rapid population increase have produced sewage problems because treatment facilities have not kept pace with need. Untreated and partially treated sewage from municipal wastewater systems and septic tanks in unsewered areas contribute significant quantities of nutrients, suspended solids, dissolved solids, oil, metals (arsenic, mercury, chromium, lead, iron, and manganese), and biodegradable organic carbon to the water environment.
Conventional pollutants may cause a myriad of water pollution problems. Excess suspended solids block out energy from the Sun and thus affect the carbon dioxide-oxygen conversion process, which is vital to the maintenance of the biological food chain. Also, high concentrations of suspended solids silt up rivers and navigational channels, necessitating frequent dredging. Excess dissolved solids make the water undesirable for drinking and for crop irrigation.
Although essential to the aquatic habitat, nutrients such as nitrogen and phosphorus may also cause overfertilization and accelerate the natural aging process (eutrophication) of lakes. This acceleration in turn produces an overgrowth of aquatic vegetation, massive algal blooms, and an overall shift in the biologic community--from low productivity with many diverse species to high productivity with large numbers of a few species of a less desirable nature. Bacterial action oxidizes biodegradable organic carbon and consumes dissolved oxygen in the water. In extreme cases where the organic-carbon loading is high, oxygen consumption may lead to an oxygen depression: (less than 2 mg/l compared with 5 to 7 mg/l for a healthy stream) is sufficient to cause a fish kill and seriously to disrupt the growth of associated organisms that require oxygen to survive.
The nonconventional pollutants include dissolved and particulate forms of metals, both toxic and nontoxic, and degradable and persistent organic carbon compounds discharged into water as a by-product of industry or as an integral part of marketable products. More than 13,000 oil spills of varying magnitude occur in the United States each year. Thousands of environmentally untested chemicals are routinely discharged into waterways; an estimated 400 to 500 new compounds are marketed each year. In addition, coal strip mining releases acid wastes that despoil the surrounding waterways. Nonconventional pollutants vary from biologically inert materials such as clay and iron residues to the most toxic and insidious materials such as halogenated hydrocarbons (DDT, kepone, mirex, and polychlorinated biphenyls--PCB). The latter group may produce damage ranging from acute biological effects (complete sterilization of stretches of waterways) to chronic sublethal effects that may go undetected for years. The chronic low-level pollutants are proving to be the most difficult to correct and abate because of their ubiquitous nature and chemical stability.
Thermal pollution is the discharge of waste heat via energy dissipation into cooling water and subsequently into nearby waterways. The major sources of thermal pollution are fossil-fuel and nuclear electric-power generating facilities and, to a lesser degree, cooling operations associated with industrial manufacturing, such as steel foundries, other primary-metal manufacturers, and chemical and petrochemical producers.
discharge temperatures from electric-power plants generally range from 5 to
The discharge of heated water into a waterway often causes ecologic imbalance, sometimes resulting in major fish kills near the discharge source. The increased temperature accelerates chemical-biological processes and decreases the ability of the water to hold dissolved oxygen. Thermal changes affect the aquatic system by limiting or changing the type of fish and aquatic biota able to grow or reproduce in the waters. Thus rapid and dramatic changes in biologic communities often occur in the vicinity of heated discharges.
Land pollution is the degradation of the Earth's land surface through misuse of the soil by poor agricultural practices, mineral exploitation, industrial waste dumping, and indiscriminate disposal of urban wastes.
Soil erosion--a result of poor agricultural practices--removes rich humus topsoil developed over many years through vegetative decay and microbial degradation and thus strips the land of valuable nutrients for crop growth. Strip mining for minerals and coal lays waste thousands of acres of land each year, denuding the Earth and subjecting the mined area to widespread erosion problems. The increases in urbanization due to population pressure presents additional soil-erosion problems; sediment loads in nearby streams may increase as much as 500 to 1,000 times over that recorded in nearby undeveloped stretches of stream. Soil erosion not only despoils the Earth for farming and other uses, but also increases the suspended-solids load of the waterway. This increase interferes with the ecological habitat and poses silting problems in navigation channels, inhibiting the commercial use of these waters.
In the United States in 1988 municipal wastes alone--that is, the solid wastes sent by households, business, and municipalities to local landfills and other waste-disposal facilities--equaled 163 million metric tons (1980 million U.S. tons), or 18 k (40lb) per person, according to figures released by the Environmental Protection Agency. Additional solid wastes accumulate from mining, industrial production, and agriculture. Although municipal wastes are the most obvious, the accumulations of other types of wastes are the most obvious, the accumulations of other types of waste are far greater, in many instances are more difficult to dispose of, and present greater environmental hazards.
The most common and convenient method of disposing of municipal solid wastes is in the sanitary landfill. The open dump, once a common eyesore in towns across the United States, attracted populations of rodents and other pests and often emitted hideous odors; it is now illegal. Sanitary landfills provide better aesthetic control and should be odor-free. Often, however, industrial wastes of unknown content are commingled with domestic wastes. Groundwater infiltration and contamination of water supplies with toxic chemicals have recently led to more active control of landfills and industrial waste disposal. Careful management of sanitary landfills, such as providing for leachate and runoff treatment as well as daily coverage with topsoil, has alleviated most of the problems of open dumping. In many areas, however, space for landfills is running out and alternatives must be found.
Recycling of materials is practical to some extent for much municipal and some industrial wastes, and a small but growing proportion of solid wastes is being recycled. When wastes are commingled, however, recovery becomes difficult and expensive. New processes of sorting ferrous and nonferrous metals, paper, glass, and plastics have been developed, and many communities with recycling programs now require refuse separation. Crucial issues in recycling are devising better processing methods, inventing new products for the recycled materials, and finding new markets for them.
Incineration is another method for disposing of solid wastes. Advanced incinerators use solid wastes as fuel, burning quantities of refuse and utilizing the resultant heat to make steam for electricity generation. Wastes must be burned at very high temperatures, and incinerator exhausts must be equipped with sophisticated scrubbers and other devices for removing dioxins and other toxic pollutants. Problems remain, however: incinerator ash contains high ratios of heavy metals, becoming a hazardous waste in itself, and high-efficiency incinerators may discourage the use of recycling and other waste-reduction methods.
Composting is increasingly used to treat some agricultural wastes, as well as such municipal wastes as leaves and brush. Composting systems can produce usable soil conditioners, or humus, within a few months (see compost).
Pesticides are organic and inorganic chemicals originally invented and first used effectively to better the human environment by controlling undesirable life forms such as bacteria, pests, and foraging insects. Their effectiveness, however, has caused considerable pollution. The persistent, or hard, pesticides, which are relatively inert and nondegradable by chemical or biologic activity, are also bioaccumulative; that is, they are retained within the body of the consuming organism and are concentrated with each ensuing level of the biologic food chain. For example, DDT provides an excellent example of cumulative pesticide effects. (Although DDT use has been banned in the United States since 1972, it is still a popular pesticide in much of the rest of the world.) DDT may be applied to an area so that the levels in the surrounding environment are less than one part per billion. As bacteria or other microscopic organisms ingest and retain the pesticide, the concentration may increase several hundred- to a thousandfold. Concentration continues as these organisms are ingested by higher forms of life--algae, fish, shellfish, birds, or humans. The resultant concentration in the higher life forms may reach levels of thousands to millions of parts per billion.
Many pesticides are nondiscriminatory; that is, they are not specific for a particular plant or organism. A dramatic example of this effect is DDE (a product of the breakdown of DDT), which effectively inhibits the ability of birds to provide sufficient calcium deposits for their eggs, producing fragile shells and a high percentage of nested eggs that break prematurely. Another reported side effect of pesticides is their effect on the nervous system of animals and fish; they can cause instability, disorientation, and, in some cases, death. These examples are generally a result of relatively high body residuals producing acute (short-term) readily recordable results.
The long-term (chronic) effects of persistent pesticides are virtually unknown, but many scientists believe they are as much an environmental hazard as are the acute effects. Nonpersistent (readily degradable) pesticides or substitutes, insect sterilization techniques, hormone homologues that check or interfere with maturation stages, and introduction of animals that prey on the pests present a potentially brighter picture for pest control with significantly reduced environmental consequences.
Radiation pollution is any form of ionizing or nonionizing radiation that results from human activities. The most well-known radiation results from the detonation of nuclear devices and the controlled release of energy by nuclear-power generating plants (see nuclear energy). Other sources of radiation include spent-fuel reprocessing plants, by-products of mining operations, and experimental research laboratories. Increased exposure to medical X rays and to radiation emissions from microwave ovens and other household appliances, although of considerably less magnitude, all constitute sources of environmental radiation.
Public concern over the release of radiation into the environment greatly increased following the disclosure of possible harmful effects to the public from nuclear weapons testing, the accident (1979) at the Three Mile Island nuclear-power generating plant near Harrisburg, Pa., and the catastrophic 1986 explosion at Chernobyl, a Soviet nuclear power plant. In the late 1980s, revelations of major pollution problems at U.S. nuclear weapons reactors raised apprehensions even higher.
The environmental effects of exposure to high-level ionizing radiation have been extensively documented through postwar studies on individuals who were exposed to nuclear radiation in Japan. Some forms of cancer show up immediately, but latent maladies of radiation poisoning have been recorded from 10 to 30 years after exposure. The effects of exposure to low-level radiation are not yet known. A major concern about this type of exposure is the potential for genetic damage.
Radioactive nuclear wastes cannot be treated by conventional chemical methods and must be stored in heavily shielded containers in areas remote from biological habitats. The safest of storage sites currently used are impervious deep caves or abandoned salt mines. Most radioactive wastes, however, have half-lives of hundreds to thousands of years, and to date no storage method has been found that is absolutely infallible.
Noise pollution has a relatively recent origin. It is a composite of sounds generated by human activities ranging from blasting stereo systems to the roar of supersonic transport jets. Although the frequency (pitch) of noise may be of major importance, most noise sources are measured in terms of intensity, or strength of the sound field. The standard unit, one decibel (dB), is the amount of sound that is just audible to the average human. The decibel scale is somewhat misleading because it is logarithmic rather than linear; for example, a noise source measuring 70 dB is 10 times as loud as a source measuring 60 dB and 100 times as loud as a source reading 50 dB. Noise may be generally associated with industrial society, where heavy machinery, motor vehicles, and aircraft have become everyday items. Noise pollution is more intense in the work environment than in the general environment, although ambient noise increased an average of one dB per year during the 1980s. The average background noise in a typical home today is between 40 and 50 decibels. Some examples of high-level sources in the environment are heavy trucks (90 dB at 15 m/50 ft), freight trains (75 dB at 15 m/50 ft), and air conditioning (60 dB at 6 m/20 ft).
The most readily measurable physiological effect of noise pollution is damage to hearing, which may be either temporary or permanent and may cause disruption of normal activities or just general annoyance. The effect is variable, depending upon individual susceptibility, duration of exposure, nature of noise (loudness), and time distribution of exposure (such as steady or intermittent). On the average an individual will experience a threshold shift (a shift in an individual's upper limit of sound detectability) when exposed to noise levels of 75 to 80 dB for several hours. This shift will last only several hours once the source of noise pollution is removed. A second physiologically important level is the threshold of pain, at which even short-term exposure will cause physical pain (130 to 140 dB). Any noise sustained at this level will cause a permanent threshold shift or permanent partial hearing loss. At the uppermost level of noise (greater than 150 dB), even a single short-term blast may cause traumatic hearing loss and physical damage inside the ear.
Although little hard information is available on the psychological side effects of increased noise levels, many researchers attribute increased irritability, lower productivity, decreased tolerance levels, increased incidence of ulcers, migraine headaches, fatigue, and allergic responses to continued exposures to high-level noises in the workplace and the general environment.
Air pollution is the accumulation in the atmosphere of substances that, in sufficient concentrations, endanger human health or produce other measured effects on living matter and other materials. Among the major sources of pollution are power and heat generation, the burning of solid wastes, industrial processes, and, especially, transportation. The six major types of pollutants are carbon monoxide, hydrocarbons, nitrogen oxides, particulates, sulfur dioxide, and photochemical oxidants.
Local and Regional
Smog has seriously affected more persons than any other type of air pollution. It can be loosely defined as a multisource, widespread air pollution that occurs in the air of cities. Smog, a contraction of the words smoke and fog, has been caused throughout recorded history by water condensing on smoke particles, usually from burning coal. The infamous London fogs--about 4,000 deaths were attributed to the severe fog of 1952--were smog of this type. Another type, ice fog, occurs only at high latitudes and extremely low temperatures and is a combination of smoke particles and ice crystals.
As a coal economy has gradually been replaced by a petroleum economy, photochemical smog has become predominant in many cities. Its unpleasant properties result from the irradiation by sunlight of hydrocarbons (primarily unburned gasoline emitted by automobiles and other combustion sources) and other pollutants in the air. Irradiation produces a long series of photochemical reactions (see photochemistry). The products of the reactions include organic particles, ozone, aldehydes, ketones, peroxyacetyl nitrate, and organic acids and other oxidants. Sulfur dioxide, which is always present to some extent, oxidizes and hydrates to form sulfuric acid and becomes part of the particulate matter. Furthermore, automobiles are polluters even in the absence of photochemical reactions. They are responsible for much of the particulate material in the air; they also emit carbon monoxide, one of the most toxic constituents of smog.
All types of smog decrease visibility and, with the possible exception of ice fog, are irritating to the respiratory system. Statistical studies indicate that smog is a contributor to malignancies of many types. Photochemical smog produces eye irritation and lacrimation and causes severe damage to many types of vegetation, including important crops. Acute effects include an increased mortality rate, especially among persons suffering from respiratory and coronary ailments. Air pollution also has a deleterious effect on works of art (see art conservation and restoration).
Air pollution on a regional scale is in part the result of local air pollution--including that produced by individual sources, such as automobiles--that has spread out to encompass areas of many thousands of square kilometers. Meteorological conditions and landforms can greatly influence air-pollution concentrations at any given place, especially locally and regionally. For example, cities located in bowls or valleys over which atmospheric inversions form and act as imperfect lids are especially likely to suffer from incidences of severe smog. Oxides of sulfur and nitrogen, carried long distances by the atmosphere and then precipitated in solution as acid rain, can cause serious damage to vegetation, waterways, and buildings.
Humans also pollute the atmosphere on a global scale, although until the
early 1970s little attention was paid to the possible deleterious effects of
such pollution. Measurements in Hawaii suggest that the concentration of carbon
dioxide in the atmosphere is increasing at a rate of about 0.2% every year. The
effect of this increase may be to alter the Earth's climate by increasing the
average global temperature. Certain pollutants decrease the concentration of
ozone occurring naturally in the stratosphere, which in turn increases the
amount of ultraviolet radiation reaching the Earth's surface. Such radiation
may damage vegetation and increase the incidence of skin cancer. Examples of
stratospheric contaminants include nitrogen oxides emitted by supersonic
aircraft and chlorofluorocarbons used as refrigerants and aerosol-can
propellants. The chlorofluorocarbons reach the stratosphere by upward mixing
from the lower parts of the atmosphere (see ozone layer). It is believed that
these chemicals are responsible for the noticeable loss of ozone over the polar
regions that has occurred in the 1980s.
Environment > Noise Pollution
Noise pollution is an increasing source of misery to many people in our society. Noise can be defined as unwanted sound. It is a source of irritation and stress for many people and can even damage our hearing if it is loud enough. Many of us are exposed to stressful levels of noise at home and at work. Noise nuisance can interfere with the individual's right to peace and quiet at home. Commonlyfourtypesofnoisearerecognised
The local environmental health department is responsible for ensuring that noise levels are kept to a minimum and for dealing with complaints from members of the public.
Noise is one form of pollution on which the efforts of the individual can have a direct effect. Although the amount of noise made by any one person or household may seem negligible, it can make a real difference to the comfort of neighbours and even other members of the household. Thefollowingsimplemeasurescanbetaken:
Noise pollution refers to undesirable levels of noises caused by human activity that disrupt the standard of living in the affected area. Noise pollution can come from:
Some noise pollution may be temporary while other sources are more permanent. Effects may include hearing loss, wildlife disturbances, and a general degradation of lifestyle.
Radioactive pollution is rare but extremely detrimental, and even deadly, when it occurs. Because of its intensity and the difficulty of reversing damage, there are strict government regulations to control radioactive pollution.
Sources of radioactive contamination include:
· Nuclear power plant accidents or leakage
Radiation pollution can cause birth defects, cancer, sterilization, and other health problems for human and wildlife populations. It can also sterilize the soil and contribute to water and air pollution.
Thermal pollution is excess heat that creates undesirable effects over long periods of time. The earth has a natural thermal cycle, but excessive temperature increases can be considered a rare type of pollution with long term effects. Many types of thermal pollution are confined to areas near their source, but multiple sources can have wider impacts over a greater geographic area.
Thermal pollution may be caused by:
· Air pollution particulates that trap heat
· Loss of temperature moderating water supplies
As temperatures increase, mild climatic changes may be observed, and wildlife populations may be unable to recover from swift changes.
Light pollution is the over illumination of an area that is considered obtrusive. Sourcesinclude:
· Nighttime sporting events and other nighttime entertainment
Light pollution makes it impossible to see stars, therefore interfering with astronomical observation and personal enjoyment. If it is near residential areas, light pollution can also degrade the quality of life for residents.
Ionizing radiation has always been a part of the human environment. Along with natural radioactive sources present in the Earth's crust and cosmic radiation, man-made sources also contribute to our continuous exposure to ionizing radiation.
Environmental radioactive pollution has resulted from past nuclear weapons testing, nuclear waste disposal, accidents at nuclear power plants, as well as from transportation, storage, loss, and misuse of radioactive sources. While there are risks associated with exposure to radiation benefits of nuclear applications in medicine industry and science are well established. WHO’s radiation programme aims to assure that the benefits of radiation technology far exceeds any known risks.
· However, solar radiation is not considered a form of pollution because it is naturally occurring. It is only capable of causing harm if one stays unprotected under its intense heat for too long. If we do, then too many of the charged particles of electromagnetic waves penetrate the human body, burn the skin, and damage the tissues and cells. The sun's ultra violet radiations are within the shortest distance from the main source, hence they are the first to reach the Earth's atmosphere.
EMF radiation emissions come from human-made sources, like electricity coming from power outlets transmitted in wave forms, and in varying degrees of frequencies. The longer the wavelength means that there is a greater distance between the receiver and the energy source and therefore, the lower the strength or intensity of radiation received. In contrast, EMFs that have shorter wave lengths have a stronger impact.
EMFs become ionizing radiation if the former meets with an atom and charges every electron component of the atom, subsequently transforming the latter into electronically charged particles and becoming ionized. The human body, as a recipient, is vulnerable to the impacts of ionizing radiation.
What Makes High Levels of Ionizing or Non-Ionizing Radiation Harmful to Humans?
Ionizing radiation becomes pollution if it fills a particular environment with high-levels of electromagnetically charged particles or ions. The effects of ionized particles in the human body depend on how far or near the human is to the EMF source. A person who accidentally touches the electric energy power of an open electrical wire receives a surge of electric current in his body called electric shock, because he touched the nearest source.
In a state of pollution, we receive these electromagnetic shocks in low frequency doses as they are released in the environment to make our mobile phones, television screens, radio transmitters, electronic appliances and the whole telecommunication system work. Hence, we are constantly receiving low frequency charged electromagnetic shocks in our body, and the multiple occurrences by which we receive those electric shocks can affect our body cells and its natural chemistry.
Non-ionizing radiation would be the opposite, which means the EMF energy transmitted is not enough to cause a particle to become electronically charged. However, based on the definition of radiation pollution, the energy transmitted, whether ionizing or non-ionizing, is harmful because it is capable of entering human bodies and affecting our systems in the same manner, as if we were receiving low doses of x-rays and gamma rays coming from multiple sources.
What are the Sources of Radiation Pollution?
Electrical transmissions of energy to power our home appliances and personal electronic gadgets are considered sources of ionizing radiation. However, these are low levels of ionization, and their effects do not pose serious detriments to human health.
There are other man-made sources of radiation that pervade the environment with more intense capabilities to penetrate the human body. It is simply because the sources of these radiation emissions were basically and intentionally designed to be powerful enough and capable of releasing energy in a single powerful blast.
Nuclear Weapons Testing Sites and Accidents
energy released is called a nuclear explosion, and its effects can be both
immediate and delayed but equally destructive. Its immediate effect is
equivalent to multiple volumes of energy described as “nuclear fallout”, and is
powerful enough to blast and burn anything within one kilometer (about
Are you familiar with these radioactive radiation pollution?
Continuation of the radiation source Nuclear Weapons Testing Sites and Accidents
The free radicals will subsequently destroy the human DNA and further disrupt the natural chemical compositions of the cells, often impairing the natural ability of cells to self-repair. The victims who received doses of radiation that went into a nuclear reaction inside their body have the potential to develop cancer, leukemia, mental defects, reproductive failure, and destruction of the immunity system.
Countries that have caused destructions to their own communities through their nuclear testing sites include the US, Russia, China, France, India, and Pakistan. Global estimates of cancer fatalities pursuant to the nuclear testing conducted by these nations are collectively placed at more than 2 million fatalities.
Solution or Remedies to this Problem:
Unfortunately, there are no solutions in the offing for this pollution source; inasmuch as the Partial Test Ban Treaty of 1963 was ignored by these countries,. Actually, these countries are regarded as racing against each other in their aim to gain recognition for having nuclear weapon supremacy.
Nuclear-Power Generating Plants
sources of radioactive pollutants in the environment are received through the
so-called “controlled release of energy by nuclear-power generating plants”.
These power plants do not release greenhouse gases but it appears that modern
nuclear power plants release radioactive gases, like Carbon 14, tritium-carbon
Solutions and remedies to this problem:
· Modern gaseous abatement techniques are being applied, which involves filtrating the release by way of dry, high-efficiency particulate aerosols to eliminate actinide aerosols. Actinide refers to the series of radioactive elements ranging from numbers 89 through 103.
· Using wet gas scrubbing to remove soluble fission products like the harmful Cesium 137 radioactive waste particles. However, the disposal of Cesium 137 waste is said to be too expensive, and currently there have been recommendations to repurpose this nuclear waste substance. Suggestions offered are their use as irradiators to kill existing and remaining bacteria in packed meat, as part of the food processing. Many are, of course, againstthis.
· Using adsorption technologies to eradicate the unstable chemically reactive gases like iodine. Adsorption mechanisms in nuclear waste management are done by way of chemical reactions that aim to create chemical bonds between the adsorption compound and the harmful chemical emissions. This way, the latter can be captured for disposal as a radioactive waste. Another term used to refer to this technique in eliminating the harmful gases in nuclear power plant releases, is “ion exchange”.
Experimental Research Laboratories
Lastly, experimental research laboratories are considered sources of ionizing radiation, polluting the environment. EMF from electrical generations are also considered as harmful but not in the same levels as those used by research laboratories during their extensive research activities. Thus, this particular source of pollution has been singled out.
The strength and intensity by which laboratories make use of electricity to power up lab equipment increases the amounts of radioactive pollutants released in the atmosphere. This increases the Radio Frequency (RF) received during transmittal of energy for telecommunication and EMFs for electronic appliance purposes.
Accordingly, radio frequencies are transmitted through the use of ionizing radiations in the form of X-ray energy; hence, technicians are greatly exposed to high levels of RF‘s ionizing x-ray radiation, and they are, likewise, emitted by the research lab to the environment in greater magnitudes.
Solutions and remedies to this problem:
The use of RF shielding fabric curtains, windows affixed with RF shield foils, and beds with shielding canopies are the recommended solutions to those living in areas near cell phone transmission towers and research labs emitting these RF emissions in high level. In addition, avoiding the use of mobile phone and cordless phone equipment within the vicinity, since these devices may be making use of more biologically damaging pulsed digital signals is advised.
As of this date, these are the known sources of radiation pollution in our environment and it is saddening to note that not everybody is aware of these radiation sources.
Strong electromagnetic fields (EMFs) of about 50 to 60 cycles per second (hertz, or Hz) and the related electromagnetic radiation (EMR) are harmful to us. Long-term exposure may aggravate any existing health problems or diseases and may cause or intensify especially lack of energy or fatigue, irritability, aggression, hyperactivity, sleep disorders and emotional instability. Increasing numbers of individuals are becoming hypersensitive to EMR; many can feel the electricity going through the body and may experience disabling symptoms such as convulsions, memory problems and depression.
Chronic exposure to high levels of EMR, especially while asleep, is a constant drain on our vitality. It creates chronic stress, which interferes with the regeneration and healing that normally takes place during a good night’s sleep. You may compare it to always swimming against a strong current and this may well make the difference between recovering from a serious disease and succumbing to it. For more information on health problems due to electricity and many case reports see www.emrsafety.8m.net.
EMR exists around power lines, power tools, electric stoves, heaters, boilers, freezers and television sets when in use, extending several feet or yards around the appliance. Stay away from them if possible. Using an electric iron or an electric keyboard or working with handheld power tools can quickly drain our energies. When working with electric equipment we can reduce harmful effects by holding our hands under running water from time to time in addition to having a shower in the evening or walking barefoot on grass.
Try to minimise electromagnetic pollution, especially while sleeping when the pineal gland is most susceptible. Also sleep in the dark or at least cover your eyes to produce the immune-stimulating hormone melatonin. Preferably switch off all power points in the bedroom and unplug all electric leads with 2-prong plugs before going to sleep but definitely any power points or leads close to the bed. This applies also to waterbeds which need to be unplugged overnight.
If the head faces a wall with power-points or other electric wiring inside the wall close to the bed then move the bed towards the middle of the room so that you can walk around the bed. The best sleeping position is with the head towards north or otherwise somewhere between north and east.
When using an electric blanket, warm the bed beforehand and pull out the plug at the wall when you go to bed. Do not habitually remain within a few metres of a working electric appliance, minimise fluorescent lighting, watching television, using video games, computers and even electric typewriters and hand-held electric tools.
Stray currents and radiating fields can still be emitted from electric wires even if appliances are switched off. AC electric fields do not disappear when an appliance is switched off, only AC magnetic fields disappear. Keep live wires away from your body. Preferably do not live near high-voltage lines, microwave towers or electric-train tracks.
Television sets also emit harmful X-rays. Preferably sit as far away as conveniently possible. The field is strongest directly in front and at the back. View the set at an angle and restrict your exposure to only a few programs daily - the fewer the better. Computer monitors apparently have stronger radiations to the sides than to the front.
Electro-proofing your house
The measures outlined so far will go some way to reduce the harmful effects of EMR on your health. However, often they are not enough. There is a simple way to check if your home and workplace are sufficiently safe. You can do this by measuring the electricity that is absorbed by your body. For this you need a digital voltmeter or multimeter, which is able to read millivolts. This is reasonably cheap to buy or a friend may lend you one.
Then you get some insulated electric wire that is long enough to reach from most rooms to the ground outside and attach an alligator clip to each end. Finally you need a ground stake or earth spike, a copper pipe is good, which you drive into the ground in moist soil. One end of the wire is clipped to a clamp at the top of the ground stake and the other to the black probe of the voltmeter. It is not good enough to attach the earth wire to a water pipe or to the main electricity ground stake of the house as they may carry high voltages.
To close the
circuit you just need to hold the metal end of the red probe firmly in one
hand. However, it is more convenient to hold a piece of copper pipe, which is
connected through a clipped or soldered insulated wire to the red probe. Now
you set the dial to
In reality the readings will be much higher and you may get between 2 and 50 V while lying on your bed. This is a constant drain on your vitality. By moving the bed away from any electrical wiring you may perhaps get it to read between 500 mV and 2 V. A relatively easy way of reducing the voltage a lot further is by using an earthed electric blanket.
The easiest way is to use an old or second-hand electric blanket and cut off the plug. Then you can easily solder or clip an earth wire onto all three-wire strands. If you want to keep using it for heating as well, then you may attach a plug to the earth wire. Lying on a well-earthed electric blanket may bring the body voltage down to read one quarter to one tenth of the previous measurement.
If the bed has a steel frame or innerspring mattress then these may also need to be earthed. Commonly all springs are internally connected and need to be earthed only at one point but some mattresses have individual springs which would need to be earthed individually. However, steel frames and innerspring mattresses still may deflect the compass needle when moved across the bed and that is not good either. The needle should continue pointing north everywhere over the bed. Metal beams in the wall or ceiling may cause the same problem and the bed should be moved far enough away from magnetic field disturbances.
In addition earth any metal parts, such as window frames, metal wall cladding or roofing iron that show an unacceptably high reading when touched with one hand while holding the earthed probe in the other. This is especially the case if there are high-voltage power-lines, microwave towers or transformers nearby or powerlines that form a right angle as at street corners.
Occasionally there may be so much ground electricity that it shows a higher reading when lying on an earthed electric blanket than without an earth connection. In this case move the earth stake as far away as possible from any power sources that may cause this problem and find or create a good earthing behind the house where you can reach moist soil with a long ground stake. With a short ground stake try to keep the soil around it moist at all times. It is also possible to get a good earth by connecting the wire to a moist part of a tree or large outside plant.
To get a true reading on a concrete floor or when outside the house you should be insulated by wearing shoes, otherwise the reading will be much too low.
For sanitising an apartment of office in a large building where you cannot get a good earth you may just try if an earth connection to the water pipe is sufficient or get expert help. An upper floor of a building commonly has much higher voltages than the ground floor, as there may be wiring in the floor as well as in the ceiling. In this case you may be able to reduce the EMR considerably by placing earthed wire netting under the carpet. If this is not possible with the entire floor, then perhaps just earth a smaller area where you are usually sitting.
In other cases it may be advisable to shield and earth the wiring inside a wall. This is much more difficult as wall panels need to be removed but it may be relatively easy under the roof or if the wiring is under the house. You may simply wrap electric cables with earthed wire netting or aluminium foil or nail metal strips over them.
In addition to these earthing measures, you may disconnect the fuse or switch in the meter-box for the bedroom (commonly including all power points in the house) overnight. Alternatively have a separate fuse switch installed for the bedroom only or a demand switch that only supplies power to the circuit when needed. In addition, strategically placed copper coils may be used and are highly recommended to de-stress the whole house. For such coils as well as digital voltmeters with hand probes, earth stakes and earth wires see Resources.
claim to have discovered harmful earthrays from fault lines and underground
streams under the beds of most cancer victims. Earthrays may also aggravate
many other diseases. Try to find someone who is able to check the location of
your bed for harmful underground radiation, even if you sleep on an upper
floor. Commonly dowsing or muscle testing (kinesiology) are used. Geopathic
disturbances can also be detected with a scientific instrument, the Geo Test
An easier but more subjective way to assess the safety of a sleeping location is muscle testing. Perform a muscle test while lying in the usual sleeping position on the bed. If the arm is weaker than with a test in another part of the bed or the room then you may have to change your sleeping location. You may also try mental testing. While your partner tests your muscle strength, imagine lying or sleeping in the bed. Then imagine an underground stream and harmful radiation underneath the bed. If the arm is stronger while imagining the usual sleeping arrangement, then your bed is likely to be in a good spot, otherwise continue the test by imagining sleeping in a different location.
If you cannot have your bed reliably checked, then move it to a different location if you were sleeping there before any health problems developed. In addition use a shielding device under the bed: place wire netting under the whole area of the bed and connect this to an electric earth. Against fault lines or ley lines you may also cover the area under the bed with several centimetres of quartz sand and use additional copper coils but moving the bed is the safest option. You may also be able to check the bed yourself with a short wave radio - over a fault line the reception deteriorates. Especially dangerous are crossings of fault lines.
All these warnings apply to the common household alternating (AC) current. Direct current (DC), on the other hand, is generally harmless, except with very high voltages, while low voltages are sometimes even used in healing. To make a car safe, electric charges at the engine, chassis, and interior need to be returned to the negative pole of the battery.
Radiation protection, sometimes known as radiological protection, is the protection of people and the environment from the harmful effects of ionizing radiation, which includes both particle radiation and high energy electromagnetic radiation.
Ionizing radiation is widely used in industry and medicine, and it presents a significant health hazard. It is also present as cosmic rays in outer space, so spacecraft and spacesuits must have appropriate shielding. It causes microscopic damage to living tissue, resulting in skin burns and radiation sickness at high exposures, and statistically elevated risks of cancer at low exposures.
Principles of radiation protection
Radiation protection can be divided into occupational radiation protection, which is the protection of workers, medical radiation protection, which is the protection of patients and the radiographer, and public radiation protection, which is protection of individual members of the public, and of the population as a whole. The types of exposure, as well as government regulations and legal exposure limits are different for each of these groups, so they must be considered separately.
There are three factors that control the amount, or dose, of radiation received from a source. Radiation exposure can be managed by a combination of these factors:
1. Time: Reducing the time of an exposure reduces the effective dose proportionally. An example of reducing radiation doses by reducing the time of exposures might be improving operator training to reduce the time they take to handle a source.
3. Shielding: The term 'biological shield' refers to a mass of absorbing material placed around a reactor, or other radioactive source, to reduce the radiation to a level safe for humans. The effectiveness of a material as a biological shield is related to its cross-section for scattering and absorption, and to a first approximation is proportional to the total mass of material per unit area interposed along the line of sight between the radiation source and the region to be protected. Hence, shielding strength or "thickness" is conventionally measured in units of g/cm2. The radiation that manages to get through falls exponentially with the thickness of the shield. In x-ray facilities, walls surrounding the room with the x-ray generator may contain lead sheets, or the plaster may contain barium sulfate. Operators view the target through a leaded glass screen, or if they must remain in the same room as the target, wear lead aprons. Almost any material can act as a shield from gamma or x-rays if used in sufficient amounts.
Practical radiation protection tends to be a job of juggling the three factors to identify the most cost effective solution.
In most countries a national regulatory authority works towards ensuring a secure radiation environment in society by setting requirements that are also based on the international recommendations for ionizing radiation (ICRP - International Commission on Radiological Protection):
Types of radiation
The total absorption coefficient of lead (atomic number 82) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Here, the photoelectric effect dominates at low energy. Above 5 MeV, pair production starts to dominate.
Different types of ionizing radiation interact in different ways with shielding material. The effectiveness of shielding is dependent on the Stopping power of radiation particles, which varies with the type and energy of radiation and the shielding material used. Different shielding techniques are therefore used dependent on the application and the type and energy of the radiation.
In some cases, improper shielding can actually make the situation worse, when the radiation interacts with the shielding material and creates that absorbs in the organisms more readily. For example, although high atomic number materials are very effective in shielding photons, using them to shield beta particles may cause higher radiation exposure due to the production of bremsstrahlung x-rays, and hence low atomic number materials are recommended. Also, using material with a high neutron activationcross section to shield neutrons will result in the shielding material itself becoming radioactive and hence more dangerous than if it were not present.
A lead castle built to shield a radioactive sample in a lab
To first approximation shielding reduces the intensity of radiation exponentially depending on the thickness.
This means when
added thicknesses are used, the shielding multiplies. For example, a practical
shield in a fallout shelter is ten halving-thicknesses of packed dirt, which is
Column Halving Mass in the chart above indicates mass of material, required to cut radiation by 50%, in grams per square centimetre of protected area.
The effectiveness of a shielding material in general increases with its density except for neutron shielding.
Graded-Z shielding is a laminate of several materials with different Z values (atomic numbers) designed to protect against ionizing radiation. Compared to single-material shielding, the same mass of graded-Z shielding has been shown to reduce electron penetration over 60%.It is commonly used in satellite-based particle detectors, offering several benefits:
Designs vary, but typically involve a gradient from high-Z (usually tantalum) through successively lower-Z elements such as tin, steel, and copper, usually ending with aluminium. Sometimes even lighter materials such as polypropylene or boron carbide are used.
In a typical graded-Z shield, the high-Z layer effectively scatters protons and electrons. It also absorbs gamma rays, which produces X-ray fluorescence. Each subsequent layers absorbs the X-ray fluorescence of the previous material, eventually reducing the energy to a suitable level. Each decrease in energy produces bremsstrahlung and Auger electrons, which are below the detector's energy threshold. Some designs also include an outer layer of aluminium, which may simply be the skin of the satellite.
Radiation protection instruments
Practical radiation measurement is essential in evaluating the effectiveness of protection measures, and in assessing the radiation dose likely to be received by individuals. The measuring instruments for radiation protection are both "installed" (in a fixed position) and portable (hand-held or transportable).
Installed instruments are fixed in positions which are known to be important in assessing the general radiation hazard in an area. Examples are installed "area" radiation monitors, Gamma interlock monitors, personnel exit monitors, and airborne contamination monitors.
The area monitor will measure the ambient radiation, usually X-Ray, Gamma or neutrons; these are radiations which can have significant radiation levels over a range in excess of tens of metres from their source, and thereby cover a wide area.
Interlock monitors are used in applications to prevent inadvertant exposure of workers to an excess dose by preventing personnel access to an area when a high radiation level is present.
Airborne contamination monitors measure the concentration of radioactive particles in the atmosphere to guard against radioactive particles being deposited in the lungs of personnel.
Personnel exit monitors are used to monitor workers who are exiting a "contamination controlled" or potentially contaminated area. These can be in the form of hand monitors, clothing frisk probes, or whole body monitors. These monitor the surface of the workers body and clothing to check if any radioactive contamination has been deposited. These generally measure alpha or beta or gamma, or combinations of these.
The UK National Physical Laboratory publishes a good practice guide through its Ionising Radiation Metrology Forum concerning the provision of such equipment and the methodology of calculating the alarm levels to be used.
Hand-held ion chamber survey meter in use
Portable instruments are hand-held or transportable. The hand-held instrument is generally used as a survey meter to check an object or person in detail, or assess an area where no installed instrumentation exists. They can also be used for personnel exit monitoring or personnel contamination checks in the field. These generally measure alpha, beta or gamma, or combinations of these.
Transportable instruments are generally instruments that would have been permanently installed, but are temporarily placed in an area to provide continuous monitoring where it is likely there will be a hazard. Such instruments are often installed on trolleys to allow easy deployment, and are associated with temporary operational situations.
In the United Kingdom the HSE has issued a user guidance note on selecting the correct radiation measurement instrument for the application concerned. This covers all radiation instrument technologies, and is a useful comparative guide.
A number of commonly used detection instruments are listed below.
The links should be followed for a fuller description of each.
Main article: ALARP
ALARP, is an acronym for an important principle in exposure to radiation and other occupational health risks and stands for "As Low As Reasonably Practicable". The aim is to minimize the risk of radioactive exposure or other hazard while keeping in mind that some exposure may be acceptable in order to further the task at hand. The equivalent term ALARA, "As Low As Reasonably Achievable", is more commonly used in the United States and Canada.
This compromise is well illustrated in radiology. The application of radiation can aid the patient by providing doctors and other health care professionals with a medical diagnosis, but the exposure should be reasonably low enough to keep the statistical probability of cancers or sarcomas (stochastic effects) below an acceptable level, and to eliminate deterministic effects (e.g. skin reddening or cataracts). An acceptable level of incidence of stochastic effects is considered to be equal for a worker to the risk in another work generally considered to be safe.
This policy is based on the principle that any amount of radiation exposure, no matter how small, can increase the chance of negative biological effects such as cancer. It is also based on the principle that the probability of the occurrence of negative effects of radiation exposure increases with cumulative lifetime dose. These ideas are combined to form the linear no-threshold model. At the same time, radiology and other practices that involve use of radiations bring benefits to population, so reducing radiation exposure can reduce the efficacy of a medical practice. The economic cost, for example of adding a barrier against radiation, must also be considered when applying the ALARP principle.
There are four major ways to reduce radiation exposure to workers or to population:
Space radiation produced by the Sun and other galactic sources is more dangerous and hundreds of times more intense than radiation sources such as medical X-rays or normal cosmic radiation usually experienced on Earth. When the intensely ionizing particles found in space strike human tissue, it can result in cell damage and may eventually lead to cancer.
The Space Radiation Laboratory makes use of a particle accelerator that produces beams of protons or heavy ions. These ions are typical of those accelerated in cosmic sources and by the Sun. The beams of ions move through a 100-meter (328-foot) transport tunnel to the 37-square-meter (400-square-foot) shielded target hall. There, they hit the target, which may be a biological sample or shielding material. In a 2002 NASA study, it was determined that materials that have high hydrogen contents, such as polyethylene, can reduce primary and secondary radiation to a greater extent than metals, such as aluminum.
Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable (from IAEA definition).
Such contamination presents a hazard because of the radioactive decay of the contaminants, which emit harmful ionising radiation such as alpha or beta particles, gamma rays or neutrons. The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable.
Contamination may affect a person, a place, an animal, or an object such as clothing. Following an atmospheric nuclear weapon discharge or a nuclear reactor containment breach, the air, soil, people, plants, and animals in the vicinity will become contaminated by nuclear fuel and fission products. A spilled vial of radioactive material like Uranyl nitrate may contaminate the floor and any rags used to wipe up the spill. Cases of widespread radioactive contamination include the Bikini Atoll, the Rocky Flats Plant in Colorado, the Fukushima Daiichi nuclear disaster, the Chernobyl disaster, and the area around the Mayak facility in Russia.
Cleaning up contamination results in radioactive waste unless the radioactive material can be returned to commercial use by reprocessing. In some cases of large areas of contamination, the contamination may be mitigated by burying and covering the contaminated substances with concrete, soil, or rock to prevent further spread of the contamination to the environment. If a person's body is contaminated by ingestion or by injury and standard cleaning cannot reduce the contamination further, then the person may be permanently contaminated.
Sources of contamination
Global airborne contamination Atmospheric nuclear weapon tests almost doubled the concentration of
Radioactive contamination is typically the result of a spill or accident during the production, or use of, radionuclides (radioisotopes); these have unstable nuclei which are subject to radioactive decay.
Contamination may occur from radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is spilled (accidentally or, as in the case of the Goiânia incident, through ignorance), the material could be spread by people as they walk around. Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive xenon in nuclear fuel reprocessing. In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. For a discussion of environmental contamination by alpha emitters please see actinides in the environment.
Contamination does not include residual radioactive material remaining at a site after the completion of decommissioning. Therefore, radioactive material in sealed and designated containers is not properly referred to as contamination, although the units of measurement might be the same.
Large industrial glovebox in the nuclear industry
Being within the intended "Containment" differentiates radioactive material from radioactive contamination. When radioactive materials are concentrated to a detectable level outside a planned containment, the area affected is generally referred to as "contaminated".
There are a large number of techniques for containing radioactive material so that it does not spread beyond the containment and become contamination. In the case of liquids this is by the use of high integrity tanks or containers, usually with a sump system so that leakage can be detected by radiometric or conventional instrumentation.
Where material is likely to become airborne, then extensive use is made of the glovebox, which is a common technique in hazardous laboratory and process operations in many industries. The gloveboxes are kept under a slight negative pressure and the vent gas is filtered in high efficiency filters, which are monitored by radiometric instrumentation to ensure they are functioning correctly.
Radioactive contamination may exist on surfaces or in volumes of material or air.
Surface contamination is usually expressed in units of radioactivity per unit of area. For SI, this is becquerels per square meter (or Bq/m²). Other units such as picoCuries per 100 cm² or disintegrations per minute per square centimeter (1 dpm/cm² = 167 Bq/m²) may be used. Surface contamination may either be fixed or removable. In the case of fixed contamination, the radioactive material cannot by definition be spread, but it is still measurable.
Detection and measurement of surface contamination of personnel and plant is normally by Geiger counter, scintillation counter or proportional counter. Proportional counters and dual phosphor scintillation counters can discriminate between alpha and beta contamination, but the Geiger counter cannot. Scintillation detectors are generally preferred for hand held monitoring instruments, and are designed with a large detection window. Geiger detectors tend to have small windows, but are more robust.
In the United Kingdom the HSE has issued a user guidance note on selecting the correct radiation measurement instrument for the application concerned. This covers all radiation instrument technologies, and is a useful comparative guide.
The spread of contamination by personnel exiting controlled areas in which nuclear material is used or processed is controlled by a variety of barrier techniques, sometimes involving changes of clothing and foot wear as required. Radiological instrumentation plays a key role in monitoring and detecting any potential contamination spread, and a combination of hand held survey instruments and permanently installed contamination monitors is used. The UK NPL publishes a guide on the alarm levels to be used with instruments for checking personnel exiting controlled areas in which contamination may be encountered.
The air can be contaminated with radioactive isotopes in particulate form, which poses a particular inhalation hazard. Respirators with suitable air filters can mitigate these dangers. Airborne contamination is measured by specialist radiometric instruments that continuously sample the air, and filter and accumulate the airborne radioactive particles so that they can be measured by an ionising radiation detector. Commonly a semiconductor radiation detection sensor is used that can also provide spectrographic information on the contamination being collected. A further refinement is to have a "moving filter" device which automatically moves the filter on incrementally to present clean areas of filter for accumulation, and thereby allow a plot of air borne concentration over time.
Internal human contamination
Radioactive contamination can enter the body through ingestion, inhalation, absorption, or injection. For this reason, it is important to use personal protective equipment when working with radioactive materials. Radioactive contamination may also be ingested as the result of eating contaminated plants and animals or drinking contaminated water or milk from exposed animals. Following a major contamination incident, all potential pathways of internal exposure should be considered.
Periodic table with elements colored according to the half-life of their most stable isotope.
Elements which contain at least one stable isotope.
Radioactive elements: the most stable isotope is very long-lived, with half-life of over four million years.
Radioactive elements: the most stable isotope has half-life between 800 and 34.000 years.
Radioactive elements: the most stable isotope has half-life between one day and 103 years.
Highly radioactive elements: the most stable isotope has half-life between several minutes and one day.
Extremely radioactive elements: the most stable isotope has half-life less than several minutes.
Low level contamination
The hazards to people and the environment from radioactive contamination depend on the nature of the radioactive contaminant, the level of contamination, and the extent of the spread of contamination. Low levels of radioactive contamination pose little risk, but can still be detected by radiation instrumentation. If a survey or map is made of a contaminated area, random sampling locations may be labeled with their activity in bequerels or curies on contact. Low levels may be reported in counts per minute using a scintillation counter.
In the case of low-level contamination by isotopes with a short half-life, the best course of action may be to simply allow the material to naturally decay. Longer-lived isotopes should be cleaned up and properly disposed of, because even a very low level of radiation can be life-threatening when in long exposure to it.
Facilities and physical locations that are deemed to be contaminated may be cordoned off by a health physicist and labeled "Contaminated area." Persons coming near such an area would typically require anti-contamination clothing or anti-c's.
High level contamination
High levels of contamination may pose major risks to people and the environment. People can be exposed to potentially lethal radiation levels, both externally and internally, from the spread of contamination following an accident (or a deliberate initiation) involving large quantities of radioactive material. The biological effects of external exposure to radioactive contamination are generally the same as those from an external radiation source not involving radioactive materials, such as x-ray machines, and are dependent on the absorbed dose.
When radioactive contamination is being measured or mapped in situ, any location that appears to be a point source of radiation is likely to be heavily contaminated. A highly contaminated location is colloquially referred to as a "hot spot." On a map of a contaminated place, hot spots may be labeled with their "on contact" dose rate in mSv/hr. In a contaminated facility, hot spots may be marked with a sign, shielded with bags of lead shot, or cordoned off with warning tape containing the radioactive trefoil symbol in magenta on a yellow background.