Instruct: Given a question, retrieve passages that can help answer the question.
Query: What is the number one air pollutant?
Carbon dioxide (CO 2) – Because of its role as a greenhouse gas it has been described as "the leading pollutant"[5] and "the worst climate pollution".[6] Carbon dioxide is a natural component of the atmosphere, essential for plant life and given off by the human respiratory system.[7] This question of terminology has practical effects, for example as determining whether the U.S. Clean Air Act is deemed to regulate CO 2 emissions.[8] CO 2 currently forms about 410 parts per million (ppm) of earth's atmosphere, compared to about 280 ppm in pre-industrial times,[9] and billions of metric tons of CO 2 are emitted annually by burning of fossil fuels.[10] CO 2 increase in earth's atmosphere has been accelerating.[11] Sulfur oxides (SOx) – particularly sulphur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Coal and petroleum often contain sulphur compounds, and their combustion generates sulphur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid 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, particularly nitrogen dioxide, are expelled from high temperature combustion, and are also produced during thunderstorms by electric discharge. They can be seen as a brown haze dome above or a plume 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 colorless, odorless, toxic yet non-irritating gas.[12] It is a product of combustion of fuel such as natural gas, coal or wood. Vehicular exhaust contributes to the majority of carbon monoxide let into our atmosphere. It creates a smog type formation in the air that has been linked to many lung diseases and disruptions to the natural environment and animals. In 2013, more than half of the carbon monoxide emitted into our atmosphere was from vehicle traffic and burning one gallon of gas will often emit over 20 pounds of carbon monoxide into the air.[13] Volatile organic compounds (VOC) – 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 enhanced global 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. Particulate matter / particles, 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,[14] altered lung function and lung cancer. Particulates are related to respiratory infections and can be particularly harmful to those already suffering from conditions like asthma.[15] Persistent free radicals connected to airborne fine particles are linked to cardiopulmonary disease.[16][17] Toxic metals, such as lead and mercury, especially their compounds. Chlorofluorocarbons (CFCs) – harmful to the ozone layer; emitted from products are currently banned from use. These are gases which are released from air conditioners, refrigerators, aerosol sprays, etc. On release into the air, CFCs rise to the stratosphere. Here they come in contact with other gases and damage the ozone layer. This allows harmful ultraviolet rays to reach the earth's surface. This can lead to skin cancer, eye disease 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. In the atmosphere, ammonia reacts with oxides of nitrogen and sulphur to form secondary particles.[18] 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.
NERI includes a number of departments devoted to various environmental and ecological categories:NERI monitors air pollution in Denmark and Greenland, and works with mathematical atmospheric dispersion models to describe transport, transformation and deposition of air pollutants. The models range in spatial resolution from local air pollution in a single street, to both nationwide and global air pollution. NERI compiles Danish emission inventories as part of Denmark's obligations in accordance with international conventions.
One popular use of HYSPLIT is to establish whether high levels of air pollution at one location are caused by transport of air contaminants from another location. HYSPLIT's back trajectories, combined with satellite images (for example, from NASA's MODIS satellites), can provide insight into whether high air pollution levels are caused by local air pollution sources or whether an air pollution problem was blown in on the wind.
Air pollution dispersion – distribution of air pollution into the atmosphere. Air pollution is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, or the natural or built environment. Air pollution may come from anthropogenic or natural sources. Dispersion refers to what happens to the pollution during and after its introduction; understanding this may help in identifying and controlling it. Air pollution dispersion has become the focus of environmental conservationists and governmental environmental protection agencies (local, state, province and national) of many countries (which have adopted and used much of the terminology of this field in their laws and regulations) regarding air pollution control.
While transnational pollution between the United States and Canada has decreased many Canadians still say they contend with polluted air as a result of drifting pollution from the U.S. In 2006 the government of Ontario announced that "5,000 premature deaths caused by smog in the province every year can be attributed to air pollution that crosses the Canada-U.S. border." Additionally, the then (2006) mayor of Halifax, Peter Kelley, also proclaimed "over 50 per cent of air pollutants over New Brunswick and Nova Scotia are from the U.S. For us, we're trying to deal with what's coming our way, but also what we generate here as well." In an attempt to combat the pollution a petition was created. In 2006 the petition was filed by thirteen Canadian municipalities to the U.S. Environmental Protection Agency calling for a reduction in coal-fired plants.
According to the National Environmental Analysis released by Tsinghua University and The Asian Development Bank in January 2013, Jinan is one of ten most air polluted cities in the world. Also according to this report, 7 of 10 most air polluted cities are in China, including Taiyuan, Beijing, Urumqi, Lanzhou, Chongqing, Jinan and Shijiazhuang. As air pollution in China is at an all-time high, several northern cities are among the most polluted cities and has one of the worst air quality in China. Reporting on China's air quality has been accompanied by what seems like a monochromatic slideshow of the country's several cities smothered in thick smog. According to a survey made by "Global voices China" in February 2013, Jinan is among China's 10 most polluted cities, and is the only Shandong city to be on this list. Other cities on the blacklist includes major Chinese cities like Beijing, Shijiazhuang, Zhengzhou, and 6 other prefectural cities all in Hebei Province. These cities are all situated in traditional geographic subdivision of "Huabei (North China) Region".
The Toxic 100 Air polluters index from the University of Massachusetts lists Precision Castparts as the number one air polluter in the U.S. in the August 2013 edition, which the company called a flawed study.
Congress added an operating permit program to the 1990 Clean Air Act for larger industries and commercial sources that release toxins into the air. These permits have information about which pollutants are emitted, how much may be emitted, and what actions the person in charge is taking to minimize the pollution. Permits must also state plans to measure and report the air pollution produced. The EPA is also responsible for making sure each state and tribe abides by the permits. For businesses that qualify for more than one thing under the Clean Air Act, operating permits are helpful because the information is all there. These permits tell them exactly what they need to do to prevent pollution. Now the EPA is more powerful in being able to enforce the rules instead of having to handle everything in court. The EPA can either "issue an order requiring the violator to comply, issue and administrative penalty order, or bring a civil judicial action".
Prior to the decision made by the Arbitral Tribunal on Trail, disputes over air pollution between two countries had never been settled through arbitration, and the polluter pays principle had never been applied in an international context. When the Tribunal dealt with the details of the Trail Smelter Arbitration, there was no existing international law that dealt with air pollution; therefore, a law dealing with international air pollution was modelled after U.S. state laws, with the Tribunal referring to a number of cases in the U.S. that involved air pollution between multiple states.
It is estimated that 24,000 lives are prematurely ended due to the effects of air pollution. Moreover, these health consequences are estimated to cost the UK £29,000 per life year lost in "good" health, £15,000 per life year lost in "poor" health and £1,900–£2,000 per hospital admission. Given the harm caused by air pollution the UK has a poor record in responding to air pollution. The European Union is currently considering prosecuting the British government for breaching air pollution laws. Air pollution near in a number of locations has been recorded at twice the UN's World Health Organization maximum recommended level, which has consequently infringed EU air quality laws. Moreover, the Environment Agency, the UK's principal environmental regulator, has what some may consider to be a poor record of prosecuting infringements of environmental standards. For example, there were 29,627 "substantiated" pollution incidents in 2003, of which 1337 were considered serious by the agency. However, in the same year the agency prosecuted 266 companies, 61 resulted in fines over £10,000. The average fine for companies was £8,412, down from £8,622 in 2002. There are approximately 20,000 incidents each year in the UK and around 250 prosecutions, which means there is a one in eighty chance of company being prosecuted for these incidents.
Air pollution often travels from its source in one state to another state. In many metropolitan areas, people live in one state and work or shop in another; air pollution from cars and trucks may spread throughout the interstate area. The 1990 Clean Air Act provides for interstate commissions on air pollution control, which are to develop regional strategies for cleaning up air pollution. The 1990 amendments include other provisions to reduce interstate air pollution.
The physical and chemical conditions that exist inside any such diesel engines under any conditions differ considerably from spark-ignition engines, because, by design, diesel engine power is directly controlled by the fuel supply, not by control of the air/fuel mixture, as in conventional gasoline engines. As a result of these differences, diesel engines generally produce a different array of pollutants than spark-driven engines, differences that are sometimes qualitative (what pollutants are there, and what are not), but more often quantitative (how much of particular pollutants or pollutant classes are present in each). For instance, diesel engines produce one-twenty-eighth the carbon monoxide that gasoline engines do, as they burn their fuel in excess air even at full load.
The Pollutant Standards Index, or PSI, is a type of air quality index, which is a number used to indicate the level of pollutants in air. 
See Your Lung Campaign:
New Delhi is termed as one of the most polluted cities in the world. Therefore, the government is doing all it can to tackle land, water and air pollution in the city. The See Your Lung campaign comes as a helping hand for it in terms of bringing forth the message of anti-pollution to the citizens.
Vijay Kannan, the founder of the See Your Lung Campaign, said that people do not realize the risk that they are putting themselves and others by using motor vehicles. He further stressed on the point that what’s the point in using a vehicle for conveyance when a cycle can do all the work.
Mr. Kannan is also the founder of the Clean India Air Movement (CLAIM) under which free car pool service was offered to around 10,000 citizens of New Delhi. CLAIM and the See Your Lung initiatives have quickly picked up the pace in terms of accomplishing their goals. The probability of the future being a bright, pollution-free one is slowly but surely turning into a reality.
Save Your Lung Campaign:
On the eve of World Asthma Day, Clean Air India Movement, launched the “Save Your Lungs” campaign to increase awareness of the ill-effects of rising air-pollution levels. Clean Air India Movement — a nationwide campaign to spread awareness about air pollution — has started from Gurgaon. The campaign will be taken to many cities across the country, including Delhi, Mumbai, Bengaluru and Kolkata.
There are 3 impact points that are influenced in Oskemen. The atmosphere is hit most. With a poor urban ventilation (the average percentage of calm 48%), with a large number of vehicles and stationary sources relevance of air pollution in Oskemen is not in doubt. The concentration of harmful substanes in the air is increasing each year because of the nature of the companies which are looking for increases in the production and profits. As usual, the pollution is enhanced by the low quality of car fuels and increase in the number of cars. As a result of all this, Oskemen is often recognized as one of the most polluted regional centers of Kazakhstan.
Air pollution is one of the major environmental issues in Isfahan. Due to an increase in the number of cars in the city, thermal power plants, petrochemical complexes and the oil refinery in the west of the city, air pollution levels have increased markedly in the second half of the 20th century. With the introduction of national environment levels for heavy industry, industrial pollution has been reduced in recent years. However, the air quality in the city is far below world norms. Indeed, Isfahan has the highest air pollution index of all the major cities in Iran. This is thought to be partly due to its climate and geography.
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
Air pollution is one of the major environmental issues in Tabriz. Air pollution is due to increase of number of cars in the commuting in the city and the polluting industries such as thermal power plants, petrochemical complexes and the oil refinery in the west of the city, air pollution levels increased continuously in the second half of the 20th century. With a mandate of national environmental codes by heavy industries the industrial air pollution is reduced in recent years. However the air quality in the city is far away from world norms for clean air.
Air pollution is commonly associated with the image of billowing clouds of smoke rising into the sky from a large factory. While the fumes and smoke previously stated definitely is a prominent form of air pollution, it is not the only one. Air pollution can come from the emission of cars, smoking, and other sources. Air pollution does not just affect birds though, like one may have thought. Air pollution affects mammals, birds, reptiles, and any other organism that requires oxygen to live. Frequently, if there is any highly dangerous air pollution, the animal observation process will be rather simple: There will be an abundance of dead animals located near the vicinity of the pollution.
There are a number of different mobile sources of air pollution, some contributing more to pollution than others. As mentioned previously, mobile sources are regulated differently from stationary sources due to the large number of sources and their ability to move from one location to another. Different mobile sources operate differently and generate different emission types and levels. The E.P.A. differentiates between mobile sources by classifying them as either on-road vehicles or non-road vehicles. On-road vehicles and non-road vehicles are often subject to different regulations.
There are a number of different pollutants that are emitted by mobile sources. Some make up a large portion of the total air concentration for that particular pollutant while others do not make up as much of the total air concentration.
EPA has ten regional offices, each of which is responsible for the execution of programs within several states and territories. EPA's website provides a detailed list of state agencies which administer the environmental regulations at the state level. California is the only state which has its own regulatory agency, the California Air Resources Board (CARB). The other states are allowed to follow CARB or federal regulations.
The Air Pollution Control Act was the culmination of much research done on fuel emissions by the federal government in the 1930s and 1940s. Additional legislation was passed in 1963 to better fully define air quality criteria and give more power in defining what air quality was to the secretary of Health, Education, and Labor. This additional legislation would provide grants to both local and state agencies. A replacement, the Clean Air Act (United States) (CAA), was enacted to replace the Air Pollution Control Act of 1955. A decade later the Motor Vehicle Air Pollution Control Act was enacted to focus more specifically on automotive emission standards. A mere two years later, the Federal Air Quality Act was established to define "air quality control regions" scientifically based on topographical and meteorological facets of air pollution.
Mobile source air pollution includes any air pollution emitted by motor vehicles, airplanes, locomotives, and other engines and equipment that can be moved from one location to another. Many of these pollutants contribute to environmental degradation and have negative effects on human health. To prevent unnecessary damage to human health and the environment, environmental regulatory agencies such as the U.S. Environmental Protection Agency have established policies to minimize air pollution from mobile sources. Similar agencies exist at the state level. Due to the large number of mobile sources of air pollution, and their ability to move from one location to another, mobile sources are regulated differently from stationary sources, such as power plants. Instead of monitoring individual emitters, such as an individual vehicle, mobile sources are often regulated more broadly through design and fuel standards. Examples of this include corporate average fuel economy standards and laws that ban leaded gasoline in the United States. The increase in the number of motor vehicles driven in the U.S. has made efforts to limit mobile source pollution challenging. As a result, there have been a number of different regulatory instruments implemented to reach the desired emissions goals.
Aside from social and economic effects, traffic congestion also has massive effects on the environment, specifically its contribution to air pollution. According to the World Health Organization (WHO), air pollution is defined as the contamination of the indoor or outdoor environment by chemical, physical, or biological means. Air pollution is an “invisible danger” that people must not ignore. Despite the fact that it cannot be seen, air pollution has affected the lives of a number of Filipinos. The WHO said that air pollution is killing millions worldwide, including those in developing countries like the Philippines. Furthermore, the Metropolitan Manila Development Authority (MMDA) noted that dirty air threatens the lives of 12 million residents.
As air pollution in China is at an all-time high, several Hebei cities are among one of the most polluted cities and has one of the worst air quality in China. Reporting on China's airpocalypse has been accompanied by what seems like a monochromatic slideshow of the country's several cities smothered in thick smog. According to a survey made by "Global voices China" in February 2013, 7 cities in Hebei including Xingtai, Shijiazhuang, Baoding, Handan, Langfang, Hengshui and Tangshan, are among China's 10 most polluted cities. Xingtai ranked 1st in the list and is referred to has the worst air quality in all Chinese cities.
Due to the number of rice mills in and around the town, the air is polluted. Rice mills emit polluted air containing carbon dioxide and other compounds of green house gas directly into the air. We can see the atmosphere turned into black every morning due to polluted air. People in the town are expecting some pollution filter methods to be used in the rice mills.