A bachelors degree in a branch of engineering, physical science, or life science that included 12 semester hours in chemistry, including organic chemistry, and 18 additional semester hours of courses in any combination of chemistry, physics, engineering, health physics, environmental health, biostatistics, biology, physiology, toxicology, epidemiology, or industrial hygiene; or. The Industrial Hygienist Series has an Individual Occupational Requirement (IOR): Applicants must meet one of the following requirements: A bachelors or graduate/higher level degree in industrial hygiene, occupational health sciences, occupational and environmental health, toxicology, safety sciences, or related science; or.