Pollution

Some chemicals and biological materials cause harm or disconfort to humans and other living organisms. When they are introduced to the atmosphere, the air becomes polluted.

The most common pollutants produced by human activity include sulphur dioxides, nitrogen oxides, carbon monoxide and carbon dioxide. High levels of fine particles in the air (particulate matter, PM) are linked to health problems such as heart disease, breathing difficulties and lung cancer.

Chemical and biological pollution of rivers and oceans can cause harm to fish, coral reefs and other aquatic life.