Hydrogen sulfide gas smells like which of the following?

• A. Rotten eggs
• B. Dead fish
• C. Rotten cabbage
• D. Fuel gas

Answer: (A)

Hydrogen sulfide has a rotten-egg odor at low concentrations, which is the classic warning sign in wastewater environments. That sulfurous, egg-like smell comes from the compound itself and is detectable even when the gas is present in tiny amounts. However, at higher concentrations the sense of smell can be overwhelmed, so you shouldn’t rely on odor alone for safety. The rotten-egg smell is the best match for this gas, while the other odors point to different chemicals—dead fish to other nitrogen-containing or amine compounds, rotten cabbage to various sulfur compounds, and fuel gas odor comes from added mercaptans used to odorize natural gas, not from hydrogen sulfide itself.