A recent study from the Lancet Commission on Pollution and Health has established that the annual death toll from environmental pollution is approximately 9 million persons, or 16% of worldwide deaths, each year. This number goes beyond the amount of deaths arising from war fatalities, AIDS, tuberculosis and malaria combined. Strikingly, more than half of those casualties are caused by air pollution.

In a collaborative research project, the WHO and the Energy Policy Institute of the University of Chicago developed the Air Quality-Life Index (AQLI) aimed at measuring the impact of air pollution on life expectancy. The findings were quite chilling: in heavily polluted regions such as Eastern China or Northern India, a person’s lifespan can be shortened by an average of three-four years; in cities like Beijing, Tianjin or New Delhi life expectancy reduction was more like 10 years.

Major outdoor pollution sources include vehicles, power generators, building heating systems, agriculture/waste incinerators and heavy industry. In addition, more than 3 billion people worldwide rely on polluting technologies and fuels (including biomass, coal and kerosene) for household cooking, heating and lighting.

Particulate Matter - air pollution - Air Quality Alliance

Particulate Matter

PM is composed of sulphates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a mixture of solid and liquid particles of organic and inorganic substances suspended in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

The most health-damaging particles are those with a diameter of 10 microns or less, (≤ PM10). These can penetrate and lodge deep inside the lungs. Chronic exposure to these particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as lung cancer.


Ozone at ground level is one of the major constituents of photochemical smog. The ozone molecule (O3) is harmful to air quality, outside of the ozone layer. Tropospheric, or ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC).

Excessive ozone in the air can have a marked effect on human health. It can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases. Several European studies have reported that mortality rates rise by 0.3% per 10 µg/m3 increase in ozone exposure.

According to the EPA, relatively low amounts of ozone can cause chest pain, coughing, shortness of breath and throat irritation. It may also worsen chronic respiratory diseases such as asthma as well as compromise the ability of the body to fight respiratory infections.

Ozone - air pollution - Air Quality Alliance
Nitrogen dioxide (NO2) - Air Quality Alliance

Nitrogen dioxide (NO2)

The major sources of anthropogenic emissions of NO2 are combustion processes. These include heating, power generation, and engine function in vehicles and ships.

Nitrogen dioxide is a particularly dangerous air pollutant because it contributes to the formation of photochemical smog, which can have significant impacts on human health.

The main effect of breathing in high levels of nitrogen dioxide is the increased likelihood of respiratory problems. Nitrogen dioxide inflames the lining of the lungs, and it can reduce immunity to lung infections. This can cause problems such as wheezing, coughing, colds, flu and bronchitis.

Increased levels of nitrogen dioxide can have significant impacts on people with asthma because it can cause more frequent and more intense attacks. Children with asthma and older people with heart disease are most at risk.

Sulphur dioxide (SO2)

The largest source of SO2 in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Smaller sources of SO2 emissions include: industrial processes such as extracting metal from minerals; natural sources such as volcanoes; diesel trains, large ships and other vehicles and heavy equipment that burn fuel with a high sulphur content. Another important source of SO2 is the burning of sulphur-containing fossil fuels for domestic heating.

Sulphur dioxide affects human health when it is breathed in. It irritates the nose, throat and airways, causing coughing, wheezing, shortness of breath and a tightening of the chest. The effects of an increase in sulphur dioxide levels are felt very quickly: most people would feel the worst symptoms within 10 – 15 minutes of exposure. Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels in the air. When SO2 combines with water, it forms sulphuric acid; this is the main component of acid rain.

Sulphur dioxide (SO2) - Air Quality Alliance
Carbon monoxide (CO) - Air Quality Alliance

Carbon monoxide (CO)

CO is released when something is burned. Natural sources of carbon monoxide include volcanoes and bushfires. The main sources of additional carbon monoxide are motor vehicle exhaust and some industrial activities, such as making steel. Tobacco smoke is one of the main indoor sources of carbon monoxide.

Increased levels of carbon monoxide reduce the amount of oxygen carried by haemoglobin in blood. The result is that vital organs, such as the brain, nervous tissues and the heart, do not receive enough oxygen to work properly.

For healthy people, a small increase in the level of carbon monoxide can cause trouble concentrating. Some people might become a bit clumsy as their coordination is affected, and they could get tired more easily.