Hydrogen Sulfide in Workplaces
Hydrogen sulfide is produced naturally from decaying organic matter. It can be released from sewage sludge, liquid manure, and sulfur hot springs, and with natural gas. It is also used or is a by-product in many industrial processes such as:
- Petroleum production and refining
- Sewer and wastewater treatment
- Agricultural silos and pits
- Textile manufacturing
- Pulp and paper processing
- Food processing
- Hot asphalt paving
Many workers are at risk for exposure to hydrogen sulfide, especially when working in confined spaces. For example,
- Sanitation workers can be exposed when cleaning or maintaining municipal sewers and septic tanks.
- Farm workers can be exposed when cleaning manure storage tanks or working in manure pits.
- Workers in oil and natural gas drilling and refining may be exposed because hydrogen sulfide may be present in oil and gas deposits and is a by-product of the desulfurization process of these fuels. See OSHA Oil and Gas Well Drilling and Servicing eTool [links directly to H2S subpage].
In general, working in the following areas and conditions increases a worker’s risk of overexposure to hydrogen sulfide:
- Confined spaces (for example pits, manholes, tunnels, wells) where hydrogen sulfide can build up to dangerous levels.
- Windless or low-lying areas that increase the potential for pockets of hydrogen sulfide to form.
- Marshy landscapes where bacteria break down organic matter to form hydrogen sulfide.
- Hot weather that speeds up rotting of manure and other organic materials, and increases the hydrogen sulfide vapor pressure.
Example of a confined space – storage silo.
For more information on the workplaces that face hydrogen sulfide hazards:
- National Occupational Exposure Survey: Hydrogen Sulfide (1981-83). National Institute for Occupational Safety and Health (NIOSH), (1990, July 1). Types of occupations and estimated number of employees potentially exposed to hydrogen sulfide.
- Health Effects of Low-Level Hydrogen Sulfide in Ambient Air [266 KB PDF, 43 pages]. Michigan Environmental Science Board, (2000, August). Includes a lengthy list of occupations with potential hydrogen sulfide exposure.
OSHA Safety and Health Information Bulletins (SHIBs)
- Chemical Exposures from Industrial Valve and Piping Systems. (1996, May 14). Discusses the potential hazard that exists for releasing hazardous chemicals into the workplace when a normally closed system is opened.
- Corrosion of Piping in Hydroprocessing Units. (1994, July 29). An explosion and fire resulted when severe corrosion caused the failure of the hydrocracking Reactor Effluent Air Coolers (REAC) and adjacent piping at a refinery.
- Confined Space Entry on Drilling Rigs. (1990, May 30). Overview of two near casualties involving confined space entry on drilling rigs.
- Anaerobic Decomposition in Cooling Water Systems. (1990, March 5). A fireball developed when a pipefitter used a cutting torch on a cooling water system pipe. Hydrogen sulfide created from anaerobic decomposition was the probable causative agent for the production of explosive gases.
Example of a confined space – vault.
Recent OSHA Citations
- U.S. Labor Department's OSHA cites excavation and utilities company following fatality at Gordon, Texas, facility (2011, December 21).
- U.S. Department of Labor's OSHA cites 5 companies for exposing workers to hydrogen sulfide at Eustace, Texas, work site (2011, April 8).
- U.S. Department of Labor's OSHA cites Matula & Matula Construction following worker death in Lake Jackson, Texas (2010, August 5).
- U.S. Labor Department's OSHA cites Enbridge G&P in Douglasville, Texas, following worker fatality from release of hydrogen sulfide (2010, July 8).
- U.S. Labor Department's OSHA cites Chipco LLC in Zanesville, Ohio, following fatality at natural gas well site in Londonderry, Ohio (2010, March 8).
- U.S. Labor Department's OSHA cites two employers following confined-space deaths at Queens, NY, recycling facility (2010, January 12).
- U.S. Department of Labor's OSHA proposes more than $1.4 million in penalties in connection with fatal explosion in Houston (2010, January 4).
Example of a confined space – vault.
- U.S. Department of Labor's OSHA cites chemical recycling company following a fatality at Port Arthur, Texas, worksite (2009, October 9).
- U.S. Department of Labor's OSHA cites Suncor Energy (U.S.A.) Inc. in Commerce City, Colo., for workplace safety and health violations (2009, March 6).
- Search all OSHA News Releases, including the Archive of Previous Years.