Ozone Ozone Ozone , or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower atmosphere to or dioxygen. Ozone is formed from dioxygen by the action of ultraviolet light (UV) and electrical discharges within the Earth's atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun's ultraviolet (UV) radiation.
Tropospheric ozone is the reaction of •OH with NO to form nitric acid at high NOx levels. If nitrogen monoxide (NO) is instead present at very low levels in the atmosphere (less than 10 approximately ppt), the of peroxy radicals (HO• ) formed from the oxidation will instead react with themselves to form peroxides, and not produce ozone. Health effects depend on ozone precursors, which is a group of pollutants, primarily generated during the combustion of fossil fuels. Reaction with daylight ultraviolet (UV) rays and these precursors create ground-level ozone pollution (Tropospheric Ozone). Ozone is known to have the following health effects