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. Nitrogen oxides are emitted from cars and power stations . Very high amounts can be recorded in cities during rush-hour traffic.