At what level in parts per million (ppm) is hydrogen sulfide considered fatal?

Hydrogen sulfide (H2S) is a colorless gas known for its distinct foul odor resembling that of rotten eggs. It is important to understand the health effects of this gas, particularly at varying concentrations. At concentrations around 300 parts per million (ppm), hydrogen sulfide can become fatal. At this level, it can quickly lead to serious respiratory distress and loss of consciousness, often without warning—as the gas can mask its presence through olfactory fatigue, meaning individuals may stop perceiving the smell after prolonged exposure.

Exposure to 300 ppm can result in severe health effects, including respiratory failure. It is crucial for individuals working in environments where hydrogen sulfide may be present to be aware of these dangers and to use appropriate safety measures and detection equipment. This context underscores why 300 ppm is recognized as a significant threshold for toxicity leading to life-threatening situations.