Air pollution

Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials.[1] It is also the contamination of indoor or outdoor surrounding either by chemical activities, physical or biological agents that alters the natural features of the atmosphere.[2] There are many different types of air pollutants, such as gases (including ammonia, carbon monoxide, sulphur dioxide, nitrous oxides, methane and

chlorofluorocarbons), particulates (both organic and inorganic), and biological molecules. Air pollution can cause diseases, allergies, and even death to humans; it can also cause harm to other living organisms such as animals and food crops, and may damage the environment (for example, climate change, ozone depletion or habitat degradation) or built environment (for example, acid rain).[3] Air pollution can be caused by both human activities[4] and natural phenomena.[5]

Air quality is closely related to the earth's climate and ecosystems globally. Many of the contributors of air pollution are also sources of greenhouse emission i.e., burning of fossil fuel.[2]

Air pollution is a significant risk factor for a number of pollution-related diseases, including respiratory infections, heart disease, COPD, stroke and lung cancer.[6] [Growing evidence suggests that air pollution exposure may be associated with reduced IQ scores, impaired cognition,[7] increased risk for psychiatric disorders such as depression[8] and detrimental perinatal health.][9] 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,[10][11] the degree of exposure, and the individual's health status and genetics.[12]

Outdoor air pollution attributable to fossil fuel use alone causes ~3.61 million deaths annually, making it one of the top contributors to human death,[6][13] with anthropogenic ozone and PM2.5 causing ~2.1 million.[14][15] Overall, air pollution causes the deaths of around 7 million people worldwide each year, or a global mean loss of life expectancy (LLE) of 2.9 years,[16] and is the world's largest single environmental health risk, which has not shown significant progress since at least 2015.[6][17][18][19] Indoor air pollution and poor 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.[20] The scope of the air pollution crisis is large: 90% of the world's population breathes dirty air to some degree. Although the health consequences are extensive, the way the problem is handled is considered largely haphazard[21][22][23] or neglected.[19]

Productivity losses and degraded quality of life caused by air pollution are estimated to cost the world economy $5 trillion per year[24][25][26] but, along with health and mortality impacts, are an externality to the contemporary economic system and most human activity, albeit sometimes being moderately regulated and monitored.[27][28] Various pollution control technologies and strategies are available to reduce air pollution.[29][30] Several international and national legislation and regulation have been developed to limit the negative effects of air pollution.[31] Local rules, when properly executed, have resulted in significant advances in public health.[32] Some of these efforts have been successful at the international level, such as the Montreal Protocol,[33] which reduced the release of harmful ozone depleting chemicals, and the 1985 Helsinki Protocol,[34] which reduced sulphur emissions,[35] while others, such as international action on climate change,[36][37][38] have been less successful.

These are mostly related to the burning of fuel.

• Stationary sources include:

• fossil-fuel power plants and biomass power plants both have smoke stacks (see for example environmental impact of the coal industry)[39]

• Oil and gas sites that have methane leaks[40][41][42][43]

• burning of traditional biomass such as wood, crop waste and dung. (In developing and poor countries, traditional biomass burning is the major source of air pollutants.[44][45] It is also the main source of particulate pollution in many developed areas including the UK & New South Wales.[46][47] Its pollutants include PAHs.[48])

• manufacturing facilities (factories)[49]

• a 2014 study found that in China equipment-, machinery-, and devices-manufacturing and construction sectors contributed more than 50% of air pollutant emissions.[50][better source needed] This high emission is due to high emission intensity and high emission factors in its industrial structure.[51]

• waste incineration (incinerators as well as open and uncontrolled fires of mismanaged waste, making up about a fourth of municipal solid terrestrial waste)[52][53]

• furnaces and other types of fuel-burning heating devices[54]

• Mobile sources include motor vehicles, trains (particularly diesel locomotives and DMUs), marine vessels and aircraft[55] as well as rockets and re-entry of components and debris.[56] The air pollution externality of cars enters the air from the exhaust gas and car tires (including microplastics[57]). Vehicles were reported to be "producing about one-third of all U.S. air pollution"[58][better source needed] and are a major driver of climate change.[59][60]

• Agriculture and forest management strategies using controlled burns. Practices like slash-and-burn in forests like the Amazon cause large air pollution with the deforestation.[61] Controlled or prescribed burning is a practice used in forest management, agriculture, prairie restoration, and greenhouse gas reduction.[62] Foresters can use controlled fire as a tool because fire is a natural feature of both forest and grassland ecology.[63][64] Controlled burning encourages the sprouting of some desirable forest trees, resulting in a forest renewal.[65]

There are also sources from processes other than combustion:

• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents. These can be substantial; emissions from these sources was estimated to account for almost half of pollution from volatile organic compounds in the Los Angeles basin in the 2010s.[66]

• Waste deposition in landfills produces methane.[67]

• Nuclear weapons, toxic gases, germ warfare, and rocketry are examples of military resources.[68]

• Agricultural emissions and emissions from meat production or livestock contribute substantially to air pollution[69][70]

• Fertilized farmland may be a major source of nitrogen oxides.[71]

Air pollutant emission factors are reported representative values that aim to link the quantity of a pollutant released into the ambient air to an activity connected with that pollutant's release.[3][77][78][79] The weight of the pollutant divided by a unit weight, volume, distance, or time of the activity generating the pollutant is how these factors are commonly stated (e.g., kilogrammes of particulate emitted per tonne of coal burned). These criteria make estimating emissions from diverse sources of pollution easier. Most of the time, these components are just averages of all available data of acceptable quality, and they are thought to be typical of long-term averages.

There are 12 compounds in the list of persistent organic pollutants. Dioxins and furans are two of them and intentionally created by combustion of organics, like open burning of plastics. These compounds are also endocrine disruptors and can mutate the human genes.