 They recommend an airborne exposure limit for ozone of 0.1ppm, which should not be exceeded at any time.The American Conference of Government Industrial Hygienists (ACGIH) is a member-based organization of industrial hygienists and individuals in the occupational and environmental health and safety industry.They recommend an airborne exposure limit of 0.05ppm for heavy work, 0.08ppm for moderate work, and 0.1ppm for light work.