افضل مواضيع جميلة بالصور

بحث عن تلوث الهواء باللغة الانجليزية

Air pollution is the introduction ofchemicals,particulates,biological materials, or other harmful materials into theEarth’s atmosphere, possibly
causing disease, death to humans, damage to other living organisms such as food crops, or
thenatural orbuilt environment.

The atmosphere is a complex natural gaseous system that is essential to support life on
planetEarth.Stratosphericozone depletion due to air pollution has long been recognized as a threat to human
health as well as to the Earth’secosystems.

Indoor air pollution (seeAirlog) and urban air quality are listed as two of the world’s
worst toxic pollution problems in the 2008Blacksmith Institute World’s Worst Polluted Places report.[1]

 

Pollutants

Schematic drawing, causes and effects of air pollution: (1) greenhouse effect, (2) particulate contamination, (3)
increased UV radiation, (4) acid rain, (5) increased ground level ozone concentration, (6) increased levels
of nitrogen oxides.

An air pollutant is a substance in the air that can have adverse effects on
humans and the ecosystem. The substance can be solid particles, liquid droplets, or gases. A
pollutant can be of natural origin or man-made. Pollutants are classified as primary or secondary.
Primary pollutants are usually produced from a process, such as ash from a volcanic eruption.
Other examples includecarbon monoxide gas from motor vehicle exhaust, or thesulfur dioxide released from factories.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants
react or interact.Ground level ozone is a prominent example of a secondary pollutant. Some pollutants
may be both primary and secondary: they are both emitted directly and formed from other
primary pollutants.

Major primary pollutants produced by human activity include:

  • Sulfur oxides (SOx) – particularly sulfur dioxide, a chemical compound with the formula SO2. SO2
    is produced by volcanoes and in various industrial processes. Coal and petroleum often contain sulfur
    compounds, and their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence
    of a catalyst such as NO2, forms H2SO4, and thusacid rain.[2] This is one of
    the causes for concern over the environmental impact of the use of these fuels as
    power sources.
  • Nitrogen oxides (NOx) – Nitrogen oxides, particularlynitrogen dioxide, are expelled from high temperature combustion, and
    are also produced duringthunderstorms byelectric discharge. They can be seen as a brownhaze dome above
    or aplume downwind of cities. Nitrogen dioxide is a chemical compound with the formula NO2.
    It is one of several nitrogen oxides. One of the most prominent air pollutants, this
    reddish-brown toxic gas has a characteristic sharp, biting odor.
  • Carbon monoxide (CO)- CO is a colourless, odourless, toxic yet non-irritating gas. It is a
    product byincomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is
    a major source of carbon monoxide.
  • Volatile organic compounds – VOCs are a well known outdoor air pollutant. They are categorized
    as either methane (CH4) or non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which
    contributes to enhancedglobal warming. Other hydrocarbon VOCs are also significant greenhouse gases because of their
    role in creating ozone and prolonging the life of methane in the atmosphere. This effect
    varies depending on local air quality. The aromatic NMVOCs benzene, toluene and xylene are suspected
    carcinogens and may lead to leukemia with prolonged exposure. 1,3-butadiene is another dangerous compound often
    associated with industrial use.
  • 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
    combined particles and gas. 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 worldwide, anthropogenic aerosols—those made by human activities—currently account for approximately 10 percent of our
    atmosphere. Increased levels of fine particles in the air are linked to health hazards such
    as heart disease,[2] altered lung — # وصلة ممنوعة 1778 # — and lung cancer.
  • Persistent free radicals connected to airborne fine particles are linked to cardiopulmonary disease.[3][4]
  • Toxicmetals, such aslead andmercury, especially their compounds.

These are gases which are released from air conditioners, refrigerators, aerosol sprays, etc. CFC’s on
being released into the air rises tostratosphere. Here they come in contact with other gases
and damage theozone layer. This allows harmful ultraviolet rays to reach the earth’s surface. This
can lead to skin cancer, disease to eye and can even cause damage to plants.

  • 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 bynuclear explosions, nuclear events, warexplosives, and natural processes such as theradioactive
    decay ofradon.

.

Secondary pollutants include:

  • Particulates created from gaseous primary pollutants and compounds in photochemical smog.Smog is a kind of
    air pollution. 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 byultraviolet
    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 minorhazardous air pollutants. Some of these are regulated in USA under
    theClean Air Act and in Europe under the Air Framework Directive
  • A variety ofpersistent organic pollutants, which can attach to particulates

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

Controlled burning of a field outside ofStatesboro,Georgia in preparation for spring planting

There are various locations, activities or factors which are responsible for releasing pollutants into the
atmosphere. These sources can be classified into two major categories.

Anthropogenic (man-made) sources:

These are mostly related to the burning of multiple types of fuel.

  • Stationary Sources include smoke stacks ofpower 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.[5][6]
  • Mobile Sources includemotor vehicles, marine vessels, and aircraft.
  • Chemicals’, dust andcontrolled burn practices in agriculture and forest 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 frompaint,hair spray,varnish,aerosol sprays and other solvents
  • Waste deposition inlandfills, which generatemethane. Methane is highly flammable and may form explosive mixtures with
    air. Methane is also anasphyxiant 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 resources, such asnuclear weapons,toxic gases,germ warfare androcketry

Natural sources:

  • Dust from natural sources, usually large areas of land with few or no vegetation
  • Methane,emitted by thedigestion of food byanimals, for examplecattle
  • Radon gas fromradioactive decay within theEarth’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, aftercigarette smoking.
  • Smoke andcarbon monoxide fromwildfires
  • 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.[7]
  • Volcanic activity, which producessulfur,chlorine, and ash particulates

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 pertonne 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 disruptors and can mutate the human genes.

TheUnited States Environmental Protection Agency has published a compilation of air pollutant emission factors for
a multitude of industrial sources.[8]TheUnited Kingdom,Australia,Canada and many other countries have published similar compilations, as
well as theEuropean Environment Agency.[9][10][11][12]

Air pollution exposure

Air pollution risk is a — # وصلة ممنوعة 1778 # — of the hazard
of the pollutant and the exposure to that pollutant. Air pollution exposure can be expressed
for an individual, for certain groups (e.g. neighborhoods or children living in a county), or
for entire populations. For example, one may want to calculate the exposure to a hazardous
air pollutant for a geographic area, which includes the various microenvironments and age groups. This
can be calculated[13] as an inhalation exposure. This would account for daily exposure in various
settings (e.g. different indoor micro-environments and outdoor locations). The exposure needs to include different age
and other demographic groups, especially infants, children, pregnant women and other sensitive subpopulaitons. The exposure
to an air pollutant must integrate the concentrations of the air pollutant with respect to
the time spent in each setting and the respective inhalation rates for each subgroup for
each specific time that the subgroup is in the setting and engaged in particular activities
(playing, cooking, reading, working, etc.). For example, a small child’s inhalation rate will be less
than that of an adult. A child engaged in vigorous exercise will have a higher
respiration rate than the same child in a sedentary activity. The daily exposure, then, needs
to reflect the time spent in each micro-environmental setting and the type of activities in
these settings. The air pollutant concentration in each microactivity/microenvironmental setting is summed to indicate the
exposure.[13]

Indoor air quality (IAQ)

Main article:Indoor air quality

Air quality monitoring, New Delhi, India.

A lack of ventilation indoors concentrates air pollution where people often spend the majority of
their time. Radon (Rn) gas, acarcinogen, is exuded from the Earth in certain locations and
trapped inside houses. Building materials includingcarpeting andplywood emitformaldehyde (H2CO) gas. Paint and solvents give offvolatile
organic compounds (VOCs) as they dry.Lead paint can degenerate intodust and be inhaled. Intentional air
pollution is introduced with the use ofair fresheners,incense, and other scented items. Controlled wood fires
in stoves andfireplaces can add significant amounts of smoke particulates into the air, inside and
out.[14] Indoor pollution fatalities may be caused by usingpesticides and other chemical sprays indoors without
proper ventilation.

Carbon monoxide (CO) poisoning and fatalities are often caused by faulty vents and chimneys, or
by the burning ofcharcoal indoors. Chroniccarbon monoxide poisoning can result even from poorly adjustedpilot lights.
Traps are built into all domesticplumbing to keep sewer gas andhydrogen sulfide, out of interiors.
Clothing emitstetrachloroethylene, or other dry cleaning fluids, for days afterdry cleaning.

Though its use has now been banned in many countries, the extensive use ofasbestos in
industrial and domestic environments in the past has left a potentially very dangerous material in
many localities.Asbestosis is a chronicinflammatory medical condition affecting the tissue of thelungs. It occurs after
long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severedyspnea (shortness of
breath) and are at an increased risk regarding several different types oflung 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 theWorld Health Organisation (WHO), these may defined as;asbestosis,lung
cancer, andPeritoneal 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, dustmites in bedding, carpeting
and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane,moldforms in walls and generatesmycotoxins
and spores,air conditioning systems can incubateLegionnaires’ disease and mold, andhouseplants, soil and surroundinggardens can producepollen,
dust, and mold. Indoors, the lack of air circulation allows these airborne pollutants to accumulate
more than they would otherwise occur in nature.

Health effects

See also:Neuroplastic effects of pollution

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.[13] 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.[15]

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.[16]
In 2024 the New York Times reported that ‘India has the highest death rate because
of chronic respiratory diseases.'[17]”Epidemiological studies suggest that more than 500,000 Americans die each year fromcardiopulmonary
disease linked to breathing fine particle air pollution. . .”[18] In December 2024 the former
health minister ofChina, Chen Zhu, a professor of medicine and a leading molecular biologist, claimed
that air pollution was killing 500,000 people in China each year.[19] A study by theUniversity
of Birmingham has shown a strong correlation betweenpneumonia related deaths and air pollution from motor
vehicles.[20] Worldwide more deaths per year are linked to air pollution than to automobile accidents.[21]
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.[22] Causes of deaths include aggravated
asthma, emphysema, lung and heart diseases, and respiratory allergies.[23] TheUS EPA estimates that a proposed
set of changes indiesel engine technology (Tier 2) could result in 12,000 fewerpremature mortalities, 15,000
fewerheart attacks, 6,000 feweremergency 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 2024 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.[24][25]

The worst short term civilian pollution crisis inIndia was the 1984Bhopal Disaster.[26] Leaked industrial vapours
from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A. (later bought over byDow
Chemical Company), 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 4Great Smog of
1952 formed overLondon. In six days more than 4,000 died, and 8,000 more died within
the following months.[citation needed] An accidental leak ofanthrax spores from abiological warfare laboratory in the formerUSSR in 1979
nearSverdlovsk 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 inDonora,
Pennsylvania in late October, 1948, when 20 people died and over 7,000 were injured.[27]

A new economic study of the health impacts and associated costs of air pollution in
theLos Angeles Basin andSan 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.[28][29][30]

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 dys– # وصلة ممنوعة 1778 # — and increased thrombus formation.[31][32] This
serves as a plausible mechanistic link between the previously described association between particulates air pollution
and increased cardiovascular morbidity and mortality.

Effects on cardiovascular health

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/m^3
increase).PMID 19235364.

Air pollution is also emerging as a risk factor for stroke, particularly in developing countries
where pollutant levels are highest.[33] A 2007 study found that in women air pollution is
associated not with hemorrhagic but with ischemic stroke.[34] Air pollution was also found to be
associated with increased incidence and mortality from coronary stroke in a cohort study in 2024.[35]
Associations are believed to be causal and effects may be mediated by vasoconstriction, low-grade inflammation
or autonomic nervous system imbalance or other mechanisms.[36][37]

Effects on cystic fibrosis

Main article:Cystic fibrosis

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 — # وصلة ممنوعة 1778 # –.[38] Patients were examined
before the study for amounts of specific pollutants likePseudomonas aeruginosa orBurkholderia cenocepacia as well as
their socioeconomic standing. Participants involved in the study were located in the United States in
close proximity to anEnvironmental Protection Agency.[39] 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 — # وصلة ممنوعة 1778 # –, everyday
pollutants such as smoke, emissions from automobiles, tobacco smoke and improper use of indoor heating
devices could further compromise lung — # وصلة ممنوعة 1778 # –.[40]

Effects on COPD and asthma

Main article:Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) includes diseases such aschronic bronchitis andemphysema.[41]

Researches have demonstrated increased risk of developing asthma[42] and COPD[43] from increased exposure to traffic-related
air pollution. Additionally, air pollution has been associated with increased hospitalizations and mortality from asthma
and COPD.[44][45]

A study conducted in 1960-1961 in the wake of theGreat 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 — # وصلة ممنوعة 1778 #
— (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.[46]

It is believed that much likecystic fibrosis, by living in a more urban environment serious
health hazards become more apparent. Studies have shown that in urban areas patients suffermucus hypersecretion,
lower levels of lung — # وصلة ممنوعة 1778 # –, and more self diagnosis
of chronic bronchitis and emphysema.[47]

Links to cancer

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 non-accidental 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
non-accidental 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 2024, 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.[48] An additional Danish study, also in 2024, likewise noted
evidence of possible associations between air pollution and other forms of cancer, including cervical cancer
and brain cancer.[49]

Effects on children

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. Air pollution is also
a significant contribution toenvironmental toxins in pregnancy.

TheWorld 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
includeEgypt,Sudan,Mongolia, andIndonesia. However even in the United States, despite the passage of theClean Air Act
in 1970, in 2002 at least 146 million Americans were living innon-attainment areas—regions in which
the concentration of certain air pollutants exceeded federal standards.[50] These dangerous pollutants are known as
thecriteria 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 asNew Delhi, India where
buses now usecompressed natural gas to help eliminate the “pea-soup” smog.[51]

Health effects in relatively “clean” areas

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 theMetro Vancouver region in 2024.[52] This finding is based on health
valuation of lethal (death) and sub-lethal (illness) affects.

Reduction efforts

There are various air pollution control technologies andland use planning strategies available to reduce air
pollution.[53][54] 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 ascruise and transport ships, farm equipment, and small
gas-powered equipment such as lawn trimmers,chainsaws, andsnowmobiles), increased fuel efficiency (such as through the use
ofhybrid vehicles), conversion to cleaner fuels (such asbioethanol,biodiesel, or conversion to electric vehicles).

Titanium dioxide has been researched for it’s ability to reduce air pollution. Ultra violet light
will release free electrons from the material creating free radicals, breaking up VOCs and NOx
gases. One form is superhydrophilic.[55]

Control devices

The following items are commonly used as pollution control devices by industry or transportation devices.
They can either destroycontaminants 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 scrubbers Wet 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.
  • Scrubbers
    • Baffle spray scrubber
    • Cyclonic spray scrubber
    • Ejector venturi scrubber
    • Mechanically aided scrubber
    • Spray tower
    • Wet scrubber
  • NOx control
    • Low NOx burners
    • Selective catalytic reduction (SCR)
    • Selective non-catalytic reduction (SNCR)
    • NOx scrubbers
    • Exhaust gas recirculation
    • Catalytic converter (also for VOC control)
  • VOC abatement
    • Adsorption systems, such asactivated carbon
    • Flares
    • Thermal oxidizers
    • Catalytic converters
    • Biofilters
    • Absorption (scrubbing)
    • Cryogeniccondensers
    • Vapor recovery systems
  • Acid Gas/SO2 control
    • Wet scrubbers
    • Dry scrubbers
    • Flue-gas desulfurization
  • Mercury control
    • Sorbent Injection Technology
    • Electro-Catalytic Oxidation (ECO)
    • K-Fuel
  • Dioxin andfuran control
  • Miscellaneous associated equipment
    • Source capturing systems
    • Continuous emissions monitoring systems (CEMS)

Legal regulations

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 AmericanAir 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.

Canada

In Canada air pollution and associated health risks are measured with theAir 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 byHealth Canada
andEnvironment 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.

12345678910+
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.

[56]

Health RiskAir Quality Health IndexHealth Messages
At Risk populationGeneral Population
Low1-3Enjoy your usual outdoor activities.Ideal air quality for outdoor activities
Moderate4-6Consider 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.
High7-10Reduce 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 highAbove 10Avoid 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.

[57]

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, andnitrogen dioxide(NO2), as well assulfur dioxide (SO2), andcarbon 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.

Germany

TA Luft is the German air quality regime.

Cities

Thefactual accuracy of parts of this article (those related to the first two images in
this section)may be compromised due to out-of-date information.Please update this article to reflect recent events
or newly available information.(October 2024)

Air pollution is usually concentrated in densely populated metropolitan areas, especially in developing countries where
environmental regulations are relatively lax or nonexistent.[58] However, even populated areas in developed countries attain
unhealthy levels of pollution withLos Angeles andRome being two good examples.[59] Between 2002 and 2024
the incidence of lung cancer inBeijing near doubled. While smoking remains the leading cause of
lung cancer in China the number of smokers is falling while lung cancer rates are
rising.[60]

National-scale air toxics assessment

Thenational-scale air toxics assessment (NATA) is EPA’s ongoing comprehensive — # وصلة ممنوعة 1775 #
–uation 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.[61]

Most Polluted World Cities by PM[62]
Particulate
matter,
μg/m³ (2004)
City
168Cairo,Egypt
150Delhi,India
128Kolkata, India (Calcutta)
125Tianjin,China
123Chongqing, China
109Kanpur, India
109Lucknow, India
104Jakarta,Indonesia
101Shenyang, China

Governing urban air pollution – a regional example (London)

InEurope, Council Directive 96/62/EC on ambient air quality assessment and management provides a common strategy
against whichmember states can “set objectives for ambient air quality in order to avoid, prevent
or reduce harmful effects on human health and the environment . . . and improve
air quality where it is unsatisfactory”.[63]

On 25 July 2008 in the case Dieter Janecek v Freistaat Bayern CURIA, theEuropean Court
of Justice ruled that under this directive[63] citizens have the right to require national authorities
to implement a short term action plan that aims to maintain or achieve compliance to
air quality limit values.[64]

This importantcase law appears to confirm the role of the EC as centralised regulator to
European nation-states as regards air pollution control. It places asupranational legal obligation on the UK
to protect its citizens from dangerous levels of air pollution, furthermore superseding national interests with
those of the citizen.

In 2024, theEuropean Commission (EC) threatened the UK with legal action against the successive breaching
ofPM10 limit values.[65] The UK government has identified that if fines are imposed, they could
cost the nation upwards of £300 million per year.[66]

In March 2024, theCity of London remains the only UK region in breach of the
EC’s limit values, and has been given 3 months to implement an emergency action plan
aimed at meeting the EU Air Quality Directive.[67] The City of London has dangerous levels
of PM10 concentrations, estimated to cause 3000 deaths per year within the city.[68] As well
as the threat of EU fines, in 2024 it was threatened with legal action for
scrapping the westerncongestion chargezone, which is claimed to have led to an increase in air
pollution levels.[69]

In response to these charges,Boris Johnson,Mayor of London, has criticised the current need for European
cities to communicate with Europe through their nation state’scentral government, arguing that in future “A
great city like London” should be permitted to bypass its government and deal directly with
the European Commission regarding its air quality action plan.[67]

In part, this is an attempt to divert blame away from the Mayor’s office, but
it can also be interpreted as recognition that cities can transcend the traditional national government
organisational hierarchy and develop solutions to air pollution using global governance networks, for example through
transnational relations. Transnational relations include but are not exclusive to national governments and intergovernmental organisations[70]
allowing sub-national actors including cities andregions to partake in air pollution control as independent actors.

Particularly promising at present are global city partnerships.[71] These can be built into networks, for
example the C40 network, of which London is a member. The C40 is a public
‘non-state’ network of the world’s leading cities that aims to curb their greenhouse emissions.[71] The
C40 has been identified as ‘governance from the middle’ and is an alternative to intergovernmental
policy.[72] It has the potential to improve urban air quality as participating cities “exchange information,
learn from best practices and consequently mitigate carbon dioxide emissions independently from national government decisions”.[71]A
criticism of the C40 network is that its exclusive nature limits influence to participating cities
and risks drawing resources away from less powerful city and regional actors.

Atmospheric dispersion

Main article:Atmospheric dispersion modeling

The basic technology for analyzing air pollution is through the use of a variety ofmathematical
models for predicting the transport of air pollutants in the lower atmosphere. The principal methodologies
are:

  • Point source dispersion, used for industrial sources.
  • Line source dispersion, used for airport androadway air dispersion modeling
  • Area source dispersion, used forforest fires orduststorms
  • Photochemical models, used to analyze reactive pollutants that form smog

Visualization of a buoyant Gaussian air pollution dispersion plume as used in many atmospheric dispersion
models.[73]

The point source problem is the best understood, since it involves simpler mathematics and has
been studied for a long period of time, dating back to about the year 1900.
It uses aGaussian dispersion model for continuous buoyant pollution plumes to predict the air pollutionisopleths,
with consideration given to wind velocity, stack height, emission rate and stability class (a measure
of atmosphericturbulence).[73][74] This model has been extensively validated and calibrated with experimental data for all
sorts of atmospheric conditions.

Theroadway air dispersion model was developed starting in the late 1950s and early 1960s in
response to requirements of theNational Environmental Policy Act and theU.S. Department of Transportation (then known
as the Federal Highway Administration) to understand impacts of proposed new highways upon air quality,
especially in urban areas. Several research groups were active in this model development, among which
were: the Environmental Research and Technology (ERT) group inLexington,Massachusetts, the ESL Inc. group inSunnyvale,California and
theCalifornia Air Resources Board group inSacramento, California. The research of the ESL group received a
boost with a contract award from theUnited States Environmental Protection Agency to validate a line
source model usingsulfur hexafluoride as a tracer gas. This program was successful in validating the
line source model developed by ESL Inc. Some of the earliest uses of the model
were in court cases involving highway air pollution, theArlington,Virginia portion ofInterstate 66 and theNew Jersey
Turnpikewidening project throughEast Brunswick,New Jersey.

Area source models were developed in 1971 through 1974 by the ERT and ESL groups,
but addressed a smaller fraction of total air pollution emissions, so that their use and
need was not as widespread as the line source model, which enjoyed hundreds of different
applications as early as the 1970s. Similarly photochemical models were developed primarily in the 1960s
and 1970s, but their use was more specialized and for regional needs, such as understanding
smog formation inLos Angeles, California.

  • بحث حول تلوث الهواء اللغة الانجليزية
  • موضوع عن تلوث الهواء باللغة الانجليزية
  • بحث حول تلوث الهواء
  • بحث عن تلوث الهواء بالانجليزي
  • موضوع عن تلوث الهواء
السابق
رسائل بنات
التالي
سيارات معدله 3d