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:
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.
A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Radon (Rn) gas, a
carcinogen, is exuded from the Earth in certain locations and trapped inside houses. Building materials including
carpeting and
plywood emit
formaldehyde (H
2CO) gas. Paint and solvents give off
volatile organic compounds (VOCs) as they dry.
Lead paint can degenerate into
dust and be inhaled. Intentional air pollution is introduced with the use of
air fresheners,
incense, and other scented items. Controlled wood fires in stoves and
fireplaces can add significant amounts of smoke particulates into the air, inside and out.
[13] Indoor pollution fatalities may be caused by using
pesticides and other chemical sprays indoors without proper ventilation.
Though its use has now been banned in many countries, the extensive use of
asbestos in industrial and domestic environments in the past has left a potentially very dangerous material in many localities.
Asbestosis is a chronic
inflammatory medical condition affecting the tissue of the
lungs. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severe
dyspnea (shortness of breath) and are at an increased risk regarding several different types of
lung cancer. As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to the
World Health Organisation (WHO), these may defined as;
asbestosis,
lung cancer, and
Peritoneal Mesothelioma (generally a very rare form of cancer, when more widespread it is almost always associated with prolonged exposure to asbestos).
Biological sources of air pollution are also found indoors, as gases and airborne particulates.
Pets produce dander, people produce dust from minute skin flakes and decomposed hair, dust
mites in bedding, carpeting and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane,
mold forms in walls and generates
mycotoxins and spores,
air conditioning systems can incubate
Legionnaires' disease and mold, and
houseplants, soil and surrounding
gardens can produce
pollen, dust, and mold. Indoors, the lack of air circulation allows these airborne pollutants to accumulate more than they would otherwise occur in nature.
Air pollution is a significant risk factor for multiple health conditions including respiratory infections, heart disease, and lung cancer, according to the WHO. The health effects caused by air pollution may include difficulty in breathing, wheezing, coughing,
asthma and aggravation of existing respiratory and cardiac conditions. These effects can result in increased medication use, increased doctor or emergency room visits, more hospital admissions and premature death. The human health effects of poor air quality are far reaching, but principally affect the body's respiratory system and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health status and genetics.
[citation needed]
The most common sources of air pollution include particulates, ozone, nitrogen dioxide, and sulfur dioxide. Both indoor and outdoor air pollution have caused approximately 3.3 million deaths worldwide. Children aged less than five years that live in developing countries are the most vulnerable population in terms of total deaths attributable to indoor and outdoor air pollution.
[14]
The World Health Organization states that 2.4 million people die each year from causes directly attributable to air pollution, with 1.5 million of these deaths attributable to indoor air pollution.
[15] "
Epidemiological studies suggest that more than 500,000 Americans die each year from
cardiopulmonary disease linked to breathing fine particle air pollution. . ."
[16] A study by the
University of Birminghamhas shown a strong correlation between
pneumonia related deaths and air pollution from motor vehicles.
[17] Worldwide more deaths per year are linked to air pollution than to automobile accidents.
[18] A 2005 study by the European Commission calculated that air pollution reduces life expectancy by an average of almost nine months across the European Union.
[19] Causes of deaths include aggravated asthma, emphysema, lung and heart diseases, and respiratory allergies.
[20] The
US EPA estimates that a proposed set of changes in
diesel engine technology (
Tier 2) could result in 12,000 fewer
premature mortalities, 15,000 fewer
heart attacks, 6,000 fewer
emergency room visits by children with asthma, and 8,900 fewer respiratory-related hospital admissions each year in the United States.
[citation needed]
The US EPA estimates allowing a ground-level ozone concentration of 65 parts per billion, would avert 1,700 to 5,100 premature deaths nationwide in 2020 compared with the current 75-ppb standard. The agency projects the stricter standard would also prevent an additional 26,000 cases of aggravated asthma, and more than a million cases of missed work or school.
[21][22]
The worst short term civilian pollution crisis in
India was the 1984
Bhopal Disaster.
[23] Leaked industrial vapours from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A., killed more than 25,000 people outright and injured anywhere from 150,000 to 600,000. The United Kingdom suffered its worst air pollution event when the December 4
Great Smog of 1952 formed over
London. In six days more than 4,000 died, and 8,000 more died within the following months.
[citation needed] An accidental leak of
anthrax spores from a
biological warfare laboratory in the former
USSR in 1979 near
Sverdlovsk is believed to have been the cause of hundreds of civilian deaths.
[citation needed] The worst single incident of air pollution to occur in the US occurred in
Donora, Pennsylvania in late October, 1948, when 20 people died and over 7,000 were injured.
[24]
A new economic study of the health impacts and associated costs of air pollution in the
Los Angeles Basin and
San Joaquin Valley of Southern California shows that more than 3800 people die prematurely (approximately 14 years earlier than normal) each year because air pollution levels violate federal standards. The number of annual premature deaths is considerably higher than the fatalities related to auto collisions in the same area, which average fewer than 2,000 per year.
[25][26][27]
Diesel exhaust (DE) is a major contributor to combustion derived particulate matter air pollution. In several human experimental studies, using a well validated exposure chamber setup, DE has been linked to acute vascular dysfunction and increased thrombus formation.
[28][29] This serves as a plausible mechanistic link between the previously described association between particulates air pollution and increased cardiovascular morbidity and mortality.
A 2007 review of evidence found ambient air pollution exposure is a risk factor correlating with increased total mortality from cardiovascular events (range: 12% to 14% per a 10 microg/m3 increase).
PMID 19235364.
Air pollution is also emerging as a risk factor for stroke, particularly in developing countries where pollutant levels are highest.
[30] A 2007 study found that in women air pollution is associated not with hemorrhagic but with ischemic stroke.
[31] Air pollution was also found to be associated with increased incidence and mortality from coronary stroke in a cohort study in 2011.
[32]
A study from around the years of 1999 to 2000, by the University of Washington, showed that patients near and around particulates air pollution had an increased risk of pulmonary exacerbations and decrease in lung function.
[33] Patients were examined before the study for amounts of specific pollutants like
Pseudomonas aeruginosa or
Burkholderia cenocepacia as well as their socioeconomic standing. Participants involved in the study were located in the United States in close proximity to an
Environmental Protection Agency.
[clarification needed] During the time of the study 117 deaths were associated with air pollution. Many patients in the study lived in or near large metropolitan areas in order to be close to medical help. These same patients had higher level of pollutants found in their system because of more emissions in larger cities. As cystic fibrosis patients already suffer from decreased lung function, everyday pollutants such as smoke, emissions from automobiles, tobacco smoke and improper use of indoor heating devices could further compromise lung function.
[34]
Researches have demonstrated increased risk of developing asthma
[36] and COPD
[37] from increased exposure to traffic-related air pollution. Additionally, air pollution has been associated with increased hosptializations and mortality from asthma and COPD.
[38][39]
A study conducted in 1960-1961 in the wake of the
Great Smog of 1952 compared 293 London residents with 477 residents of Gloucester, Peterborough, and Norwich, three towns with low reported death rates from chronic bronchitis. All subjects were male postal truck drivers aged 40 to 59. Compared to the subjects from the outlying towns, the London subjects exhibited more severe respiratory symptoms (including cough, phlegm, and dyspnea), reduced lung function (
FEV1 and peak flow rate), and increased sputum production and purulence. The differences were more pronounced for subjects aged 50 to 59. The study controlled for age and smoking habits, so concluded that air pollution was the most likely cause of the observed differences.
[40]
It is believed that much like
cystic fibrosis, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas patients suffer
mucus hypersecretion, lower levels of lung function, and more self diagnosis of chronic bronchitis and emphysema.
[41]
A review of evidence regarding whether ambient air pollution exposure is a risk factor for cancer in 2007 found solid data to conclude that long-term exposure to PM2.5 (fine particulates) increases the overall risk of nonaccidental mortality by 6% per a 10 microg/m3 increase.
PMID 19235364- Exposure to PM2.5 was also associated with an increased risk of mortality from lung cancer (range: 15% to 21% per a 10 microg/m3 increase) and total cardiovascular mortality (range: 12% to 14% per a 10 microg/m3 increase). PMID 19235364
The review further noted that living close to busy traffic appears to be associated with elevated risks of these three outcomes (increase in lung cancer deaths, cardiovascular deaths, and overall nonaccidental deaths.
PMID 19235364
The reviewers also found suggestive evidence that exposure to PM2.5 is positively associated with mortality from coronary heart diseases and exposure to SO2 increases mortality from lung cancer, but the data was insufficient to provide solid conclusions.
In 2011, a large Danish epidemiological study found an increased risk of lung cancer for patients who lived in areas with high nitrogen oxide concentrations. In this study, the association was higher for non-smokers than smokers.
[42] An additional Danish study, also in 2011, likewise noted evidence of possible associations between air pollution and other forms of cancer, including cervical cancer and brain cancer.
[43]
Around the world, children living in cities with high exposure to air pollutants are at increased risk of developing asthma, pneumonia and other lower respiratory infections. Because children are outdoors more and have higher minute ventilation they are more susceptible to the dangers of air pollution. Risks of
low initial birth weight are also heightened in such cities.
The
World Health Organization reports that the greatest concentrations of particulates are found in countries with low economic world power and high poverty and population growth rates. Examples of these countries include
Egypt,
Sudan,
Mongolia, and
Indonesia. However even in the United States, despite the passage of the
Clean Air Act in 1970, in 2002 at least 146 million Americans were living in
non-attainment areas—regions in which the concentration of certain air pollutants exceeded federal standards.
[44] These dangerous pollutants are known as the
criteria pollutants, and include ozone, particulates, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead.
Protective measures to ensure children's health are being taken in cities such as
New Delhi, India where buses now use
compressed natural gas to help eliminate the "pea-soup" smog.
[45]
Even in the areas with relatively low levels of air pollution, public health effects can be significant and costly, since a large number of people breathe in such pollutants. A 2005 scientific study for the British Columbia Lung Association showed that a small improvement in air quality (1% reduction of ambient PM2.5 and ozone concentrations) would produce a $29 million in annual savings in the
Metro Vancouver region in 2010.
[46] This finding is based on health valuation of lethal (death) and sub-lethal (illness) effects.
There are various air pollution control technologies and
land use planning strategies available to reduce air pollution.
[47][48] At its most basic level land use planning is likely to involve zoning and transport infrastructure planning. In most developed countries, land use planning is an important part of social policy, ensuring that land is used efficiently for the benefit of the wider economy and population as well as to protect the environment.
Efforts to reduce pollution from mobile sources includes primary regulation (many developing countries have permissive regulations),
[citation needed] expanding regulation to new sources (such as
cruise and transport ships, farm equipment, and small gas-powered equipment such as lawn trimmers,
chainsaws, and
snowmobiles), increased fuel efficiency (such as through the use of
hybrid vehicles), conversion to cleaner fuels (such as
bioethanol,
biodiesel, or conversion to electric vehicles).
The following items are commonly used as pollution control devices by industry or transportation devices. They can either destroy
contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.
- Particulate control
- Mechanical collectors (dust cyclones, multicyclones)
- Electrostatic precipitators An electrostatic precipitator (ESP), or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas (such as air) using the force of an induced electrostatic charge. Electrostatic precipitators are highly efficient filtration devices that minimally impede the flow of gases through the device, and can easily remove fine particulates such as dust and smoke from the air stream.
- Baghouses Designed to handle heavy dust loads, a dust collector consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system (distinguished from air cleaners which utilize disposable filters to remove the dust)
- Particulate scrubbersWet scrubber is a form of pollution control technology. The term describes a variety of devices that use pollutants from a furnace flue gas or from other gas streams. In a wet scrubber, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the liquid, by forcing it through a pool of liquid, or by some other contact method, so as to remove the pollutants.
- Miscellaneous associated equipment
In general, there are two types of air quality standards. The first class of standards (such as the U.S. National Ambient Air Quality Standards and E.U. Air Quality Directive) set maximum atmospheric concentrations for specific pollutants. Environmental agencies enact regulations which are intended to result in attainment of these target levels. The second class (such as the North American Air Quality Index) take the form of a scale with various thresholds, which is used to communicate to the public the relative risk of outdoor activity. The scale may or may not distinguish between different pollutants.
In Canada air pollution and associated health risks are measured with the The
Air Quality Health Index or (AQHI). It is a health protection tool used to make decisions to reduce short-term exposure to air pollution by adjusting activity levels during increased levels of air pollution.
The Air Quality Health Index or "AQHI" is a federal program jointly coordinated by
Health Canada and
Environment Canada. However, the AQHI program would not be possible without the commitment and support of the provinces, municipalities and NGOs. From air quality monitoring to health risk communication and community engagement, local partners are responsible for the vast majority of work related to AQHI implementation. The AQHI provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. Occasionally, when the amount of air pollution is abnormally high, the number may exceed 10. The AQHI provides a local air quality current value as well as a local air quality maximums forecast for today, tonight and tomorrow and provides associated health advice.
| Risk: | Low (1-3) | Moderate (4-6) | High (7-10) | Very high (above 10) |
As it is now known that even low levels of air pollution can trigger discomfort for the sensitive population, the index has been developed as a continuum: The higher the number, the greater the health risk and need to take precautions. The index describes the level of health risk associated with this number as ‘low’, ‘moderate’, ‘high’ or ‘very high’, and suggests steps that can be taken to reduce exposure.
| Health Risk | Air Quality Health Index | Health Messages |
|---|
| | At Risk population | General Population |
| Low | 1-3 | Enjoy your usual outdoor activities. | Ideal air quality for outdoor activities |
| Moderate | 4-6 | Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms. | No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation. |
| High | 7-10 | Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy. | Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation. |
| Very high | Above 10 | Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion. | Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation. |
It is measured based on the observed relationship of Nitrogen Dioxide (NO2), ground-level Ozone (O3) and particulates (PM2.5) with mortality from an analysis of several Canadian cities. Significantly, all three of these pollutants can pose health risks, even at low levels of exposure, especially among those with pre-existing health problems.
When developing the AQHI, Health Canada’s original analysis of health effects included five major air pollutants: particulates,
ozone, and
nitrogen dioxide (NO2), as well as
sulfur dioxide (SO
2), and
carbon monoxide (CO). The latter two pollutants provided little information in predicting health effects and were removed from the AQHI formulation.
The AQHI does not measure the effects of odour,
pollen, dust, heat or humidity.
Air pollution is usually concentrated in densely populated metropolitan areas, especially in developing countries where environmental regulations are relatively lax or nonexistent
[citation needed]. However, even populated areas in developed countries attain unhealthy levels of pollution with
Los Angeles and
Rome being two good examples.
[51]
The National-Scale Air Toxics Assessment (NATA) is EPA's ongoing comprehensive evaluation of air toxics in the U.S. EPA developed the NATA as a state-of-the-science screening tool for State/Local/Tribal Agencies to prioritize pollutants, emission sources and locations of interest for further study in order to gain a better understanding of risks. NATA assessments do not incorporate refined information about emission sources, but rather, use general information about sources to develop estimates of risks which are more likely to overestimate impacts than underestimate them. NATA provides estimates of the risk of cancer and other serious health effects from breathing (inhaling) air toxics in order to inform both national and more localized efforts to identify and prioritize air toxics, emission source types and locations which are of greatest potential concern in terms of contributing to population risk. This in turn helps air pollution experts focus limited analytical resources on areas and or populations where the potential for health risks are highest. Assessments include estimates of cancer and non-cancer health effects based on chronic exposure from outdoor sources, including assessments of non-cancer health effects for Diesel Particulate Matter (PM). Assessments provide a snapshot of the outdoor air quality and the risks to human health that would result if air toxic emissions levels remained unchanged.
[52]
