The Effects of Hydrogen Sulfide

PPM* Effects and Symptoms Time
10 Permissible Exposure Level 8 Hours
50-100 Mild Eye Irritation, Mild
Respiratory Irritation
1 Hour
200-300 Marked Eye Irritation, Marked
Respiratory Irritation
1 Hour
500-700 Unconsciousness, Death ½-1 Hour
1000 or More Unconsciousness, Death Minutes
These values are approximate and vary as to the individual’s state of health and his physical activities.
Although the foul odor (rotten eggs) of hydrogen sulfide is easily detected at low concentrations, it is an unreliable warning because the gas rapidly desensitizes the olfactory (sense of smell) nerves and leads to a false sense of security. In high concentrations of hydrogen sulfide, a worker may collapse with little or no warning.

*PPM – Parts Per Million – volume measurement of gas concentration.