What is ozone?
Ozone is a highly reactive, unstable connection of three oxygen atoms. The word itself is derived from the Greek ozein, wheach means 'to smell'. No without reason, because the gas has a typical odour that is sometimes noticeable in badly ventilated places with many (old) copying machines or after a thunderstorm with a lot of lightning. The chemical formula is O3.
Ozone in the ozone layer (in the stratosphere at a height of 15 to 45 km) protects the earth's surface against the harmful solar UV radiation.
Ozone in the lower air layer (the troposphere) at ground level is formed on hot days by the influence of sunlight (UV of ultraviolet light) on air polluted with nitrous oxides ad volatile organic compounds.