Other Pollutants

Carbon monoxide (CO) is a colorless and odorless gas that comes from burning fuel. The main sources of carbon monoxide in our cities are cars, buses and trucks. Carbon monoxide can be harmful to our health because it prevents our blood getting the amount of oxygen it needs. This can make us drowsy and make exercise difficult.

Nitrogen dioxide (NO2) is a light brown gas that is sometimes found in the brown haze over our cities. It is usually produced by cars and factories but can also be produced by heaters and gas stoves. Nitrogen dioxide causes breathing problems and is particularly bad for people with asthma.

Particulate matter (PM) is the name given to very small pieces of solid or liquid matter that float in the air. It comes from smoke, dust, ash and vapors. These particles are very small and can cause serious health problems. They make breathing difficult, especially for those people who already have lung problems.

Sulfur dioxide (SO2) is a colorless and odorless gas. It is produced when fossil fuels and ores containing sulfur are burned - often in power plants and industrial boilers. Sulfur dioxide also causes breathing problems, and makes some lung diseases even worse. It can cause you to wheeze and cough, and make you short of breath while exercising.