Science and art devoted to the anticipation, recognition, evaluation, prevention, and control of those environmental factors or stresses arising in or from the workplace which may cause sickness, impaired health and well being, or significant discomfort among workers or among citizens of the community.
An industrial hygienist is a person with a college or university degree or degrees in engineering, chemistry, physics, medicine, or related physical and biological sciences who, by virtue of special studies and training, has acquired competence in industrial hygiene. Such special studies and training must have been sufficient in all of the above cognate sciences to provide the abilities to anticipate and recognize environmental factors and to understand their effect on humans and their well-being, to evaluate on the basis of experience and with the aid of quantitative measurement techniques) the magnitude of these stresses in terms of ability to impair human health and well-being, and to prescribe methods to eliminate, control, or reduce such stresses when necessary to alleviate their effects.
Source: American Industrial Hygiene Association (AIHA)