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Air Quality

Air pollution is major cause of premature death, debilitation, and loss of life quality, as well as causing local, regional and global problems for all living systems. Air pollution also has serious negative effects for economies, not least of which are hundreds of millions of lost workdays per year.

The main sources of anthropogenic air pollution are industry, construction, transport, and agriculture. Each of these can create a range of differing pollutants, with very variant consequences for the human population and ecosystems.

Even if some air pollutants are non-toxic, they can still cause serious problems. For example, carbon dioxide from vehicle and industrial emissions does not harm the local human population breathing it, but is a major cause of the changes to the global atmosphere, leading to the enhanced greenhouse effect and global warming.


Here is a list of some major air pollutants. The figures given are typical for a developed country.

Carbon Dioxide C02

Sources

Fossil fuels: 34% power generation, 3% road vehicles, 14% domestic (heating), 28% industry and commercial

Range

Global

Effects

Principal cause of the enhanced greenhouse effect, which is responsible for the observed gobal warming and climate change. Carbon dioxide is one of the at least eight gases released by human activity which alter the atmospheric characteristics, principally infrared radiation and re-radiation, resulting in a retention of re-radiated heat by the atmosphere.

Counter-measures

Proposed transition of economies from inefficient, fossil-fuel based to more efficient and less fossil-dependent economies. In particular, industry and power generation are subject to restrictions, and the Kyoto Protocol provides for the financial instrument of carbon credits (IET market), which puts a price on carbon emissions, according to the Polluter Pays Principle. Much research and government-backed incentives promote the use of alternatives to fossil fuels in all areas of C02 generation, in particular renewable energy schemes and subsidised markets.

Outlook

Global C02 emissions have continued to rise, despite increasing evidence of the veracity of global warming. The actions of the USA in undermining the Kyoto Protocol has led to its ineffectiveness in curbing emerging economies from adopting dirty technologies, rather than committing to the clean technology mechanism proposed by Kyoto.

There are indications that political awareness may yet bring about the widespread adoption of existing and new technologies, and that very dirty practices, such as shale oil, will be prevented from undoing any progress made. The USA is leading the obstruction lobby, as before.


Sulphur Oxides S0x

S0x refers to the group of sulphur and oxygen compounds, mainly: S0, S02, and S03.

Sources

Fossil fuels (mainly coal): 72% power generation, 18% industry, 2% road vehicles, 3% domestic (heating)

Range

Local and Regional

Effects

Atmospheric particulates lead to respiratory diseases, and sulphur oxides lead to regional acid rain.

Counter-measures

To prevent the kind of smog events, such as London's Great Smog of 1952, which killed more than 12,000 people, and injured 100,000, coal has been banned for domestic heating in many countries. Flue gases are scrubbed to remove most sulphur from power station emissions, and prior-purification of fuels can eliminate much sulphur from combustion sources.

Outlook

In MDCs (more developed countries), the dependence on sulphur-bearing fuel (mainly low-grade oil) is decreasing, and the technology to scrub flue gases is finding more widespread use. In emerging economies, S0x remains a primary pollutant, with increasingly serious local and regional consequences for human and ecosystem health.


Nitrous Oxides N0x

N0x refers to the group of nitrogen and oxygen compounds, mainly: N0 N20 and N02.

Sources

Fossil fuels (mainly petrol and diesel): 51% road vehicles, 28% power generation, 10% industry, 2% domestic (heating)

Range

Local and Regional

Effects

N0x is a cause of photosmog, responsible for the development of terrestrial ozone, and other pollutants which cause respiratory ailments and disease. N0x joins S0x in forming cloud-borne acid rain (nitrous oxide), which damages property, crops and natural systems far beyond the immediate region of the source.

Counter-measures

Vehicle emissions can be reduced to some degree at source through catalytic converters, and improved fuel quality. However, the scale of the problem leads to some cities imposing traffic limiting regulations, especially in summer, when photosmog is most prevalent.

Outlook

The transition from fossil fuels to renewable energy sources will lead to reductions in this principal pollutant. Low-emission vehicle solutions such as hydrogen fuel cells, promise to reduce emissions. However, some proposed solutions, such as electric vehicles, can result in only shifting the location of the pollution emission source, rather than solve the overall pollution problem.


Volatile Organic Compounds VOCs

Volatile Organic Compounds are carbon-based compounds with a low boiling point and high vapour pressure at room temperature.

Sources

Pollution forecast
Satellite image of pollution over China: the forecast is not good

Industry and commerce give rise to a broad range of VOCs, such as from paint solvents. VOCs are produced by incomplete burning in combustion engines and furnaces.

Range

Local and regional

Effects

Though not highly toxic, VOCs can be caustic and lead to health issues, such as respiratory, eye and skin problems. Some VOCs are implicated in the chemical reactions leading to photochemical smog. VOCs may result from or cause water contamination, and be transported by watercourses.

Counter-measures

Air and water regulations restrict the production, storage, transport and use of a specified number of anthropogenic VOCs. The substitution of aqueous solvents for aliphatic hydrocarbons, ethyl acetate, glycol ethers, and acetone in paints and surface treatments, can eliminate these VOC hazards.

Outlook

Estimates put a global emission level at more than 140 teragrams (140 million tonnes) of airborne VOCs. One group of VOCs, CFCs, responsible for the breakdown of the ozone layer in the stratosphere, are largely banned, and the ozone 'hole' may have been stabilised.


Particulate Matter

Respirable suspended particles ( < 10 µm in diameter (PM10)), fine particles (< 2.5 µm (PM2.5)), aerosols, and other microscopic and macroscopic particles suspended in the air.

Sources

Anthropogenic and natural.

Range

Local, regional, and global.

Effects

Smog

PM can be breathed into the lungs, where, if fine enough, it can enter the bronchioles and alveoli, causing lung cancer and other respiratory diseases. Toxins may also enter the blood stream. Regional smog, such as the South-East Asia cloud, can cause changes to precipitation patterns, and cause pollution of land and water. Aerosols and PM are also inculpated in atmospheric changes, in particular as radiative forcing elements in climate change (so-called 'global dimming').

Counter-measures.

Fuel efficiency, filtering and catalytic converters. The ban on domestic heating with coal in major western cities has led to a significant reduction in particulate emissions. In industry, indoor and local pollution has been reduced by legislation imposing the use of technologies, such as cyclonic separators, filters, wet flue scrubbers, and electrostatic precipitators. Particulate matter is a serious pollution problem for China, with a very large economic cost, as well as public health burden.

Outlook

Ever stricter regulations, improved public awareness and technologies, have led to an improvement in smog levels in many countries. Vehicle emissions, particularly diesel, still load many PMs into the atmosphere. As developing countries increase their vehicle traffic and power consumption per capita levels, PMs will take an increasing toll on the health of the populations and ecosystems, unless cleaner technology is adopted.

Perennial and Seasonal Smog

Asian Brown Cloud

Just how bad systematic failure to curb air pollution can get can be seen in the perennial cloud of smog, which covers large areas of the Indian Ocean and countries from south-east Asia to Pakistan. The cloud intensifies between January and March, during the dry season related to the winter monsson. The monsoon rains clear the air of the pollutants.

As opposed to the specific forest fire cause of the south-east Asia haze, the Asian Brown cloud is caused by an accumulation of all types of air pollution which produce particulate matter, industry, vehicle emissions, and incomplete combustion of biomass.

South-east Asia Haze

This cloud is caused by the burning of forest, legal and illegal, in Indonesia and Malaysia.

Content © Andrew Bone. All rights reserved. Created : June 2, 2015 Last updated :November 28, 2015

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