This criteria document presents recommended standards for occupational exposure to formaldehyde (50000). Criteria presented are designed to protect against injury from formaldehyde; allow measurement by valid, reproducible procedures available to industry and official agencies; and be attainable by using existing technology. Sources of formaldehyde exposure include aqueous solutions such as formalin, and formaldehyde yielding substances such as trioxane, paraformaldehyde, polyoxymethylene, and hexamethylene-tetramine. Recommendations are provided for monitoring of workplace air, labeling and posting of hazardous materials, personal protective equipment and clothing, work practices and engineering controls and sanitation methods. Also covered are biological effects of exposure, environmental data, and occupational research priorities for formaldehyde. The section on work practices includes information on injury prevention, eye protection, skin protection, various kinds of respiratory devices, ventilation of rooms, monitoring the air, protective clothing and equipment, and hazards of explosion.