The chemical compound hydrogen sulfide has the formula (). It's a translucent chalcogen-hydride gas that's hazardous, caustic, and fiery, with tiny levels in the ambient air throwing off a rotten-egg aroma.
Hydrogen sulfide (H2S) is a gas widely observed during crude oil and natural gas drilling and production, such as in waste water treatment, utility facilities, and sewers. Microbial breakdown of organic molecules in the absence of oxygen leads to gas production.
What should do if hydrogen sulfide() is present:
Unless there is gas present, the space or region must be vented on a continuous basis to evacuate the gas. If the gas cannot be dissipated in any way, the person entering the space/area must dress appropriately for respiratory protection as well as any other personal protective equipment, rescue, and communication equipment that may be warranted.
When dealing with a hydrogen sulfide gas leak, the National Oceanic and Atmospheric Administration recommend showering the gas with water first, then neutralization it with sodium bicarbonate.
When hydrogen sulfide levels in the environment would be less than 20 parts per million (20 ppm), the presence of hydrogen sulfide can be undetected (since it doesn't pose a threat to human health at this concentration). If the concentration of H2S is larger than this, however, respiratory protection or other personal protective equipment may be required.