This paper focuses on the origin of the concepts of occupational exposure limit, and traces the history and development of thoughts and regislations of various countries and organizations concerning the founding principles upon which it is based. The concepts of establishing standards for occupational chemicals in workplace air constitute a social consensus or agreement about acceptable levels of occupational hygiene. The level of scientific development of a country and the discussion of experts in the field of occupational health play an important role. The physician in occurational health has to be especially concerned to discover and estimate the risks to anyone particularly susceptible to exposures within the hygienically acceptable conditions.