Pollutant Fact Files
Look up the fact files about these nasty pollutants!
Ozone occurs naturally in our atmosphere. High up in the atmosphere, ozone is very useful. It helps to protect us from the sun by filtering out harmful ultraviolet rays. At ground level however, it's harmful to breathe and can make breathing difficult, especially for people with asthma.
Most ground-level ozone is not emitted as a pollutant but is formed as a result of a reaction between sunlight and other pollutants. Once formed, ozone is gobbled up by nitric oxide (NO) which is usually found in towns and cities near roads. As a result, ozone pollution is more of a problem in the countryside - especially on hot, sunny days.