What is the smell of hydrogen sulphide?

Hydrogen sulfide is both an irritant and a chemical asphyxiant. It disrupts oxygen use and affects the central nervous system. Health effects depend on dose and duration; repeated exposure can cause effects at levels previously tolerated.

• Low concentrations: Irritation of eyes, nose, throat, and respiratory tract (burning/tearing, cough, shortness of breath). Asthmatics may have breathing difficulty. Effects can be delayed by hours or even days.
• Moderate concentrations: Marked eye and airway irritation, cough, dyspnea, pulmonary edema risk, headache, dizziness, nausea, vomiting, ataxia, and agitation.

Exposure

• Primary route: Inhalation; rapid lung absorption.
• Skin: Minimal absorption.
• Odor: “Rotten egg” smell detectable at low levels, but olfactory fatigue occurs with continuous low exposure or high concentrations, so the gas may be present without any odor warning.