Print page

Air pollution

Ferrybridge power station. View of electricity pylons and chimneys

Image: Andy Hay

Pollution of the atmosphere has been a problem since the Industrial Revolution.

We pollute the air with smoke and fumes from fires, factories and power stations, and from cars and other vehicles.

A great variety of substances are released into our environment. Many of these are waste products from industry, agriculture or private homes, that enter the air, rivers, the sea and the land. Occasionally, substances may escape by accident. Where these substances are in amounts that do harm to the environment, we regard them as pollutants.

The RSPB is often asked for information about pollution and how it affects birds. This is a difficult question to answer, because many of the effects of pollution do not show in an obvious way or kill birds outright. They build up slowly, so that we only notice gradually that the numbers of particular bird species are decreasing. It is almost impossible to say - except in a major incident like an oil spill - that an individual bird has died as a result of pollution. However, pollution can affect birds through the food-chains. For example, there may be less food for birds.

These are some of the main air pollution problems:

Sulphur dioxide

Sulphur dioxide gas is produced when materials containing sulphur are burned. It comes from industry, power stations, the burning of fossil fuels, and from car exhausts. The infamous London 'smogs' in the 1950s contained large amounts of sulphur dioxide from burning coal. Sulphur dioxide affects the respiratory (breathing) system of humans, particularly when combined with smoke. It also dissolves in rainwater, causing acid rain (see below).

Sulphur dioxide is still produced by burning smokeless fuels and oil. Wildlife varies in its sensitivity to this pollution - some species are very sensitive, while others are very tolerant. Some plants called lichens are particularly vulnerable. They can be useful indicators of the amount of pollution in the atmosphere.

Nitrogen oxides

Nitrogen oxide comes from vehicles and factories. It is a toxic and irritant gas, which affects the respiratory system of humans. When nitrogen dioxide dissolves in rainwater it causes acid rain (see below). Nitrogen oxide reacts with sunlight to produce a gas called ozone, which can be hazardous to humans and wildlife.

Carbon dioxide

Carbon dioxide occurs naturally in the atmosphere with other gases such as nitrogen, oxygen and water vapour. The carbon dioxide and water vapour act as a sort of "blanket" and trap the heat from the sun in the atmosphere, keeping the Earth warm. This is called the "greenhouse effect" . Carbon dioxide is often called a "greenhouse gas" .

Human activities, such as the burning of fossil fuels (coal, oil and gas), produce carbon dioxide. It is produced when anything organic is burned, and comes from power stations, factories, cars and other vehicles, and from burning down forests. These human activities are adding lots more carbon dioxide to the Earth's atmosphere, and the atmosphere is changing. The extra carbon dioxide causes more heat to be held within the atmosphere. This is popularly known as " global warming" , and is leading to changes in the world's climate.


Particulates is the word used to describe solid particles in the air. You can see them as a dark dirty coating on surfaces in towns. Smoke from burning coal has been a threat to human health. During the 1950s certain weather conditions used to cause smogs in our cities. Since the introduction of the Clean Air Acts, cities are much cleaner.

Carbon particles (which look like tiny pieces of soot) come mainly from lorries and buses that use diesel. They may cause respiratory problems in humans. Motor vehicles create more and more pollution in towns.

Carbon monoxide and lead

Motor exhaust fumes contain a poisonous gas, carbon monoxide. Levels of this gas may be high in heavy slow-moving traffic in built-up areas. When it is breathed in, it gets into the bloodstream, where it combines with the red pigment haemoglobin. This blocks the uptake of oxygen and can be fatal.

Lead is a poisonous heavy metal. It has been added to petrol and paint, and it was used as lead weights for fishing, and as shot for shooting wildfowl. Lead poisoning affects the health and survival of animals and humans. Exhaust fumes contain lead. Breathing in a lot of fumes can be dangerous. Lead in the environment is beginning to decline. There are now stricter controls in the use of lead in paints and in field sports (see the RSPB fact-sheet on Freshwater Pollution), and more cars use unleaded fuel. Leaded petrol is banned throughout European Union from year 2000.

Further reading

The RSPB has produced a series of fact-sheets on pollution: Air pollution; Land pollution; Freshwater pollution; Marine pollution; The greenhouse effect, climate change and wildlife. We have also compiled a reading list of references on pollution. All these are available from Wildlife Enquiries on 01767 680551.

Thanks to Dr Martin Stannistreet, Environmental Education Reseach Unit, University of Liverpool, UK for Children' s Models of Understanding of Two Major Global Environmental Issues.

Information in this report is taken from Climate Change and Wildlife, published by WWF and Bird Life, and The implications of global climate change for biodiversity, RSPB.