At what exposure level can hydrogen sulfide be fatal?

Hydrogen sulfide (H2S) is a toxic gas known for its characteristic smell of rotten eggs and can pose significant health risks, especially at higher concentrations. The correct exposure level at which hydrogen sulfide can be fatal is 300 ppm. At this concentration, the gas can lead to rapid loss of consciousness and respiratory failure, often resulting in death if immediate measures are not taken.

It's important to note that lower concentrations of hydrogen sulfide can still be harmful and produce symptoms like irritation of the eyes, nose, and throat, along with pulmonary effects. For example, exposure at levels around 100 ppm can cause discomfort and respiratory irritation, while levels of 150 ppm can lead to more severe symptoms and potential loss of consciousness after only a few minutes. However, 300 ppm represents a critical threshold where fatalities can occur quickly without intervention, emphasizing the importance of protective measures and monitoring in environments where hydrogen sulfide may be present.