[Man, the environment and ozone]

Ozone is a naturally occurring gas, formed in the trimolecular reaction of oxygen atoms with molecular oxygen. Its strong absorption in the UV region provides protection from excessive irradiation of the Earth's surface. Occupational exposure to ozone involves electric arc welding, mercury vapour lamps, office photocopy machines, X-ray generators and other high voltage electrical equipment, water purification and bleaching. Ozone is the most abundant oxidant in the photochemical smog. The lung cell injury induced by ozone involves a complex biochemical mechanism which is due to free radical generation. Moderate exposure produces upper respiratory tract symptoms and eye irritation, severe acute exposure results in pulmonary oedema. Measurements of atmospheric ozone concentrations in Croatia began at the end of the 19th century; continuous monitoring has been carried out since 1975.