An air pollutant is any unwanted substance or chemical that contaminate the air that we breathe resulting in a decline in air quality.
Air pollutants occur both outdoors and indoors .
Outdoor pollutants include smoke, carbon monoxide, nitrogen oxides, sulphur dioxide, particulates and ozone. Smoke is a type of pollution that can be seen because it is made up of solid particles. You can often see it coming out of chimneys. Carbon monoxide is a pollutant that is mainly produced by cars . It has no colour or smell but can be very poisonous.