Hydrogen Sulfide (H₂S) Remediation

Hydrogen Sulfide (H₂S) is a colorless, toxic, highly flammable gas with a foul, pungent odor similar to that of rotten eggs odor at low concentrations and is not detectable by odor at high concentrations.

Often referred to as “sewer gas,” H₂S is a result of the breakdown of organic matter by bacteria, typically in an oxygen deprived environment such as sewer systems or wastewater treatment plants.

H₂S is a nuisance that can pose extreme safety hazards for personnel.

MSDS – Safety Sheet

Chemical symbol: H₂S

Specific Gravity: 1.192 (heavier than air)

Explosive limits: Lower: 4% , Upper: 44% volume in air

Ignition Temperature: 500o F

Solubility in water: 2.9 volumes of gas , per volume of water at 20o C

What Are The Effects of Hydrogen Sulfide?

Hydrogen Sulfide is an extremely toxic and irritating gas. Free hydrogen sulfide in the blood reduces its oxygen-carrying capacity, thereby depressing the nervous system. Hydrogen sulfide is oxidized quite rapidly to sulfates in the body, therefore no permanent aftereffects occur in cases of recovery from acute exposures unless oxygen deprivation of the nervous system is prolonged. There is no evidence that repeated exposures to hydrogen sulfide result in accumulative or systemic poisoning. Effects such as eye irritation, respiratory tract irritation, slow pulse rate, lassitude, digestive disturbances, and cold sweats may occur but these symptoms disappear in a relatively short time after removal from the exposure.

Odors become detectable in concentrations as low as .008 parts per million (ppm)
but the sense of smell is lost after 2-15 minutes at 100 ppm.

Physiological response:

To avoid discomfort, the (8 hour) time weighted average concentration of hydrogen sulfide shall not exceed 10 ppm.

This information excerpted from the American National Standards Institute standard: Z37.2-1972 Acceptable Concentrations of Hydrogen Sulfide.

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