What is air pollution?
The air contains substances that can be harmful to health and the environment. Air pollutants include ozone, oxides of nitrogen, ammonia, sulphur dioxide, carbon monoxide and particulate matter (bits of soot, dust or liquid, for example).
What causes air pollution?
Nowadays the main threat to clean air comes from car and road vehicle fumes. Cars and lorries burn petrol and diesel, giving off air pollutants like oxides of nitrogen and particulate matter. These can cause problems for people, wildlife and the environment. Power stations and some industrial processes also produce sulphur dioxide and oxides of nitrogen among other pollutants.