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  • Cornell Cooperative Extension
  • Animal Science

Hydrogen sulfide is a highly toxic gas that can be released from the breakdown of manure in pits, tanks, and storages. It is heavier than air and can settle into low spots and accumulate in confined spaces. High concentrations can also be released during manure agitation and pumping.

While hydrogen sulfide has a characteristic “rotten egg” smell at trace levels, at dangerous and fatal levels it has destroyed the sense of smell. Thus, odor cannot be used to warn of its presence! The following table, adapted from OSHA, shows health effects associated with hydrogen sulfide concentration.



Health effects associated with hydrogen sulfide concentration

Ways to stay safe

  • Review safety with your crew before, and maintain frequent communication during, each job.
  • Use personal hydrogen sulfide gas monitors that detect the presence of hydrogen sulfide and alert the wearer of dangerous concentrations. They can be easily purchased for less than $100.
  • Set up and stay up wind of a manure storage during agitation and pump-out.
  • Never climb inside a pit, tank, or enter a confined space containing manure without the proper training and safety equipment.
  • Do not try to rescue someone who has collapsed without self-contained breathed apparatus (SCBA) training and equipment. Sadly, many fatalities associated with hydrogen sulfide include those who were attempting a rescue without SCBA equipment. Instead, try to use blowers or fans to provide fresh air and exhaust the toxic vapors if you can, and call 911.

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