Fluorine is the 13th element in order of abundance and occurs throughout man's environment. Airborne fluorides in very low concentrations may be introduced into pristine atmospheres from sources such as volcanic actions, dusts picked up by winds blowing over surface soils and weathered rocks, and from sea spray. Urban and surburban atmospheres may contain higher concentrations derived from burning fossil fuels and from miscellaneous effluents disseminated from a variety of industrial point sources. A number of states now have standards regulating the concentrations of fluoride which may be present in the air or released to the ambient air. Higher concentrations may be encountered in the work place, but again, limits selected to protect the worker from significant effects are in force. The principal effect of industrial fluoride‐containing dust to be protected against is the excessive deposition of fluoride in the skeleton. This condition, skeletal fluorosis, was recognized in Danish cryolite workers in the mid‐1930s. While mild degrees of skeletal fluorosis are occasionally seen today, no case of crippling fluorosis has yet been reported in the U.S. Gaseous fluorides may cause irritation and inflammation of the skin and of the surfaces of the respiratory tract and, in acute episodes, may produce burns. Adequate air sampling and analytical techniques are now available to ensure that airborne fluoride concentrations are in compliance with existing standards. Reasonably good knowledge of the metabolism of fluoride in man has permitted the development of biological monitoring procedures for workers to ensure that the first signs of unusual fluoride exposure are promptly detected.