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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.
1. Pollutants 2. Sources 2.1. Anthropogenic sources 2.2. Natural sources 3. Health effects 4. Reduction efforts List of Literature
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.
Indoor air pollution and urban air quality are listed
as two of the World’s Worst Toxic Pollution Problems in the 2008 Blacksmith
Institute World's Worst Polluted Places report.
A substance in the air that can be adverse 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 produced from
a process, such as ash from a volcanic eruption, the carbon monoxide
gas from a motor vehicle exhaust or sulfur 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
Sulfur oxides (SOx) - especially sulfur dioxide,
a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial
processes. Since coal and petroleum often contain sulfur compounds,
their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for
concern over the environmental impact of the use of these fuels as power
Nitrogen oxides (NOx) - especially nitrogen dioxide
are expelled from high temperature combustion, and are also produced
naturally during thunderstorms by electric discharge. Can be seen as
the brown haze dome above or plume downwind of cities. Nitrogen dioxide
is the chemical compound with the formula NO2. It is one of the several nitrogen oxides. This
reddish-brown toxic gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants.
Carbon monoxide (CO)- is a colourless, odourless,
non-irritating but very poisonous gas. It is a product by incomplete
combustion of fuel such as natural gas, coal or wood. Vehicular exhaust
is a major source of carbon monoxide.
Volatile organic compounds - VOCs are an important
outdoor air pollutant. In this field they are often divided into the
separate categories of methane (CH4) and non-methane (NMVOCs). Methane is an extremely
efficient greenhouse gas which contributes to enhanced global warming.
Other hydrocarbon VOCs are also significant greenhouse gases via their
role in creating ozone and in prolonging the life of methane in the
atmosphere, although the effect varies depending on local air quality.
Within the NMVOCs, the aromatic compounds benzene, toluene and xylene
are suspected carcinogens and may lead to leukemia through prolonged
exposure. 1,3-butadiene is another dangerous compound which is often
associated with industrial uses.
Particulates, alternatively referred to as particulate
matter (PM), atmospheric particulate matter, or fine particles, are
tiny particles of solid or liquid suspended in a gas. In contrast, aerosol
refers to particles and the gas together. Sources of particulates can
be man made or natural. Some particulates occur naturally, originating
from volcanoes, dust storms, forest and grassland fires, living vegetation,
and sea spray. Human activities, such as the burning of fossil fuels
in vehicles, power plants and various industrial processes also generate
significant amounts of aerosols. Averaged over the globe, anthropogenic
aerosols—those made by human activities—currently account for about 10 percent of the total
amount of aerosols in our atmosphere. Increased levels of fine particles
in the air are linked to health hazards such as heart disease, altered
lung function and lung cancer.
Persistent free radicals connected to airborne fine
particles could cause cardiopulmonary disease.
Toxic metals, such as lead and mercury, especially
Chlorofluorocarbons (CFCs) - harmful to the ozone
layer emitted from products currently banned from use.
Ammonia (NH3) - emitted from agricultural processes. Ammonia
is a compound with the formula NH3. It is normally encountered as a gas with a characteristic
pungent odor. Ammonia contributes significantly to the nutritional needs
of terrestrial organisms by serving as a precursor to foodstuffs and
fertilizers. Ammonia, either directly or indirectly, is also a building
block for the synthesis of many pharmaceuticals. Although
in wide use, ammonia is both caustic and hazardous.
Odors — such as from garbage, sewage, and industrial processes
Radioactive pollutants - produced by nuclear explosions,
nuclear events, war explosives, and natural processes such as the radioactive
decay of radon.
Secondary pollutants include:
Particulates created from gaseous primary pollutants
and compounds in photochemical smog. Smog is a kind of air pollution;
the word "smog" is a portmanteau of smoke and fog. Classic
smog results from large amounts of coal burning in an area caused by
a mixture of smoke and sulfur dioxide. Modern smog does not usually
come from coal but from vehicular and industrial emissions that are
acted on in the atmosphere by ultraviolet light from the sun to form
secondary pollutants that also combine with the primary emissions to
form photochemical smog.
Ground level ozone (O3) formed from NOx and VOCs.
Ozone (O3) is a key constituent of the troposphere. It is
also an important constituent of certain regions of the stratosphere
commonly known as the Ozone layer. Photochemical and chemical reactions
involving it drive many of the chemical processes that occur in the
atmosphere by day and by night. At abnormally high concentrations brought
about by human activities (largely the combustion of fossil fuel), it
is a pollutant, and a constituent of smog.
Peroxyacetyl nitrate (PAN) - similarly formed from
NOx and VOCs.
Minor air pollutants include:
A large number of minor hazardous air pollutants.
Some of these are regulated in USA under the Clean Air Act and in Europe
under the Air Framework Directive
A variety of persistent organic pollutants, which
can attach to particulates
Persistent organic pollutants 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 refers 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 (man-made
sources) mostly related to burning different kinds of fuel
"Stationary Sources" include smoke stacks
of power plants, manufacturing facilities (factories) and waste incinerators,
as well as furnaces and other types of fuel-burning heating devices.
In developing and poor countries, traditional biomass burning is the
major source of air pollutants; traditional biomass includes wood, crop
waste and dung.
"Mobile Sources" include motor vehicles,
marine vessels, aircraft and the effect of sound etc.
Chemicals, dust and controlled burn practices in
agriculture and forestry management. Controlled or prescribed burning
is a technique sometimes used in forest management, farming, prairie
restoration or greenhouse gas abatement. Fire is a natural part of both
forest and grassland ecology and controlled fire can be a tool for foresters.
Controlled burning stimulates the germination of some desirable forest
trees, thus renewing the forest.
Fumes from paint, hair spray, varnish, aerosol sprays
and other solvents
Waste deposition in landfills, which generate methane.
Methane is highly flammable and may form explosive mixtures with air.
Methane is also an asphyxiant and may displace oxygen in an enclosed
space. Asphyxia or suffocation may result if the oxygen concentration
is reduced to below 19.5% by displacement.
Military, such as nuclear weapons, toxic gases, germ
warfare and rocketry
Dust from natural sources, usually large areas of
land with few or no vegetation
Methane, emitted by the digestion of food by animals,
for example cattle
Radon gas from radioactive decay within the Earth's
crust. Radon is a colorless, odorless, naturally occurring, radioactive
noble gas that is formed from the decay of radium. It is considered
to be a health hazard. Radon gas from natural sources can accumulate
in buildings, especially in confined areas such as the basement and
it is the second most frequent cause of lung cancer, after cigarette
Smoke and carbon monoxide from wildfires
Vegetation, in some regions, emits environmentally
significant amounts of VOCs on warmer days. These VOCs react with primary
anthropogenic pollutants—specifically, NOx, SO2, and anthropogenic organic
carbon compounds—to produce a seasonal haze of secondary pollutants.
Volcanic activity, which produce sulfur, chlorine,
and ash particulates
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.
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.
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.
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.
"Epidemiological studies suggest that more than 500,000 Americans
die each year from cardiopulmonary disease linked to breathing fine
particle air pollution. . ." A study by the University of Birmingham
has shown a strong correlation between pneumonia related deaths and
air pollution from motor vehicles. Worldwide more deaths per year are
linked to air pollution than to automobile accidents. 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. Causes
of deaths include aggravated asthma, emphysema, lung and heart diseases,
and respiratory allergies. The US EPA estimates that a proposed set
of changes in diesel engine technology 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.
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.
The worst short term civilian pollution crisis in
India was the 1984 Bhopal Disaster. 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. 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. 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.
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.
Diesel exhaust 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.
This serves as a plausible mechanistic link between the previously described
association between particulates air pollution and increased cardiovascular
morbidity and mortality.
There are various air pollution control technologies
and land use planning strategies available to reduce air pollution.
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),
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).
List of Literature:
1.Andersen, Z. J., Bonnelykke, K., Hvidberg, M.,
Jensen, S. S., Ketzel, M., Loft, S., Raaschou-Nielsen, O. (2011). «Long-term
exposure to air pollution and asthma hospitalisations in older adults:
a cohort study».
2. London Assembly Environment Committee (2009).
"Every Breath You Take".
3. House of Commons Environmental Audit Committee
(2010). "Environmental Audit Committee - Fifth Report Air Quality
Загрязнение воздуха - введение в атмосферу химикатов, макрочастиц
или биологических материалов, которые
вызывают дискомфорт, болезнь, или смерть
людям, повреждают другие живые организмы,
такие как продовольственные зерновые
культуры или повреждают окружающую среду
или искусственную среду.
сложная динамическая естественная газообразная
система, которая важна, чтобы поддержать
жизнь на планете Земле. Стратосферическое
истощение озона из-за загрязнения воздуха
долго признавалось угрозой здоровью
человека так же как экосистемам Земли.
воздуха в помещении и городское качество
воздуха перечислены как две из Худших
Токсичных проблем Загрязнения В мире
в Институте Кузнеца 2008 года Худший Загрязненный
отчет о Местах В мире.
воздухе, который может быть неблагоприятным
людям и окружающей среде, известно как
воздушный загрязнитель. Загрязнители
могут быть в форме твердых частиц, жидких
капелек или газов. Кроме того, они могут
быть естественными или искусственными.
Загрязнители могут быть классифицированы
как основные или вторичные. Обычно, основные
загрязнители непосредственно произведены
из процесса, такого как пепел от извержения
вулкана, газ угарного газа от выхлопа
автомашины или двуокись серы, выпущенная
из фабрик. Вторичные загрязнители не
испускаются непосредственно. Скорее
они формируются в воздухе, когда основные
загрязнители реагируют или взаимодействуют.
Важный пример вторичного загрязнителя
- озон уровня земли — один из многих вторичных
загрязнителей, которые составляют фотохимический
смог. Некоторые загрязнители могут быть
и основными и вторичными: то есть, они
и испускаются непосредственно и формируются
из других основных загрязнителей.