Ozone (O3) - In the upper levels of the earth's atmosphere ozone forms a protective layer filtering out harmful UV rays from the sun.
At ground level, however, ozone is present as a secondary pollutant. As such it is not emitted into the air, but is a product of chemical reactions of other pollutants such as VOCs (volatile organic compounds) and NOx (oxides of nitrogen) in sunlight. Therefore, ground level ozone is often higher on hot, sunny days.
Ozone is an irritant to the delicate tissues of the body such as the eyes, nose and lungs.
Detailed information about ground level ozone can be found at the following links:
