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OSHA Standards

Hydrogen sulfide exposure is covered under the following OSHA standards:

Worker Exposure Limits (Enforceable)
  • General Industry:29 CFR 1910.1000 TABLE Z-2, Toxic and hazardous substances

    Exposures must not exceed 20 parts per million (ppm) (ceiling) with the following exception: if no other measurable exposure occurs during the 8-hour work shift, exposures may exceed 20 ppm, but not more than 50 ppm (peak), for a single time period up to 10 minutes.

  • Construction:29 CFR 1926.55 Appendix A, Gases, vapors, fumes, dusts, and mists

    Sets exposure limit of 10 ppm (15 mg/m3) time-weighted average (TWA)

  • Shipyard: 29 CFR 1915.1000 Table Z, Air contaminants

    Sets exposure limit of 10 ppm (15 mg/m3) TWA

29 CFR 1910.119 App A and 29 CFR 1926.64 App A, List of highly hazardous chemicals, toxics and reactives (mandatory). Hydrogen sulfide is included in these lists of toxic and reactive highly hazardous chemicals and is considered to present a potential for a catastrophic event at or above 1500 pounds.

Below are standards that include OSHA requirements for evaluating (e.g., process safety, toxic and hazardous substances) and controlling (ventilation, respiratory protection) hydrogen sulfide exposures, including in confined spaces. Industry-specific requirements (construction, shipyard, marine terminals and longshoring) follow.

General Industry (29 CFR 1910)

Construction (29 CFR 1926)

  • 1926 Subpart D, Occupational health and environmental control
    • 1926.55, Gases, vapors, fumes, dusts, and mists
    • Appendix A, 1970 American Conference of Governmental Industrial Hygienists' Threshold Limit Values of Airborne Contaminants
  • 1926 Subpart S, Underground construction, caissons, cofferdams, and compressed air

Shipyard Employment (29 CFR 1915)

  • 1915 Subpart B – Confined and enclosed spaces and other dangerous atmospheres in shipyard employment
    • 1915.12, Precautions and the order of testing before entering confined and enclosed spaces and other dangerous atmospheres
  • 1915 Subpart Z, Toxic and hazardous substances

Marine Terminals (29 CFR 1917)

  • 1917.1, Marine terminals, scope and applicability
  • 1917.73, Terminal facilities handling menhaden and similar species of fish

Safety and Health Regulations for Longshoring (29 CFR 1918)

  • 1918.1, Safety and health regulations for longshoring, scope and application
  • 1918.94(f), Ventilation and atmospheric conditions. Employees shall not enter the hold when the hydrogen sulfide level exceeds 20 ppm ceiling or when the oxygen content is less than 19.5 percent, except in emergencies.

Letters of Interpretation (supplementary guidance that clarifies the application of an established Agency policy or procedure)

Other Exposure Limits for
Hydrogen Sulfide

NIOSH Recommended Exposure Limit (REL): 10 ppm, 10-minute ceiling

Concentration considered immediately dangerous to life and health (IDLH): 100 ppm

ACGIH® recommends a threshold limit value (TLV®) of 1 ppm as an 8-hour time weighted average (TWA) and a short-term exposure limit (STEL) of 5 ppm.

State Standards

Twenty-five states, Puerto Rico and the Virgin Islands have OSHA-approved State Plans, which are required to be at least as effective as Federal OSHA, but may adopt their own standards and enforcement policies. However, most have adopted standards that are identical to Federal OSHA. Other federal standards related to agricultural operations are included for reference.

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