The Safe Limits of Hydrogen Sulfide Gas for Air Quality

Most people would not associate any amount of hydrogen sulfide gas with good air quality due to its infamous odor. However, knowing safe airborne limits for hydrogen sulfide gas is essential to preventing illness and death.

High Levels

Hydrogen sulfide gas can be deadly at high air concentrations. OSHA requires that workers not be exposed to hydrogen sulfide levels exceeding 50 parts per million (ppm) for more than 10 minutes during an eight-hour day. OSHA considers a concentration at or greater than 100 ppm to be "immediately dangerous to life and health."

Low Levels

Chronic exposure to hydrogen sulfide gas at low levels can also cause adverse health effects. The EPA recommends a lifetime exposure limit of 0.7 parts per billion (ppb), a residential limit of 15 ppb, a property line limit of 70 ppb and a 0.14 ppb limit for children and the elderly.

Odor

Hydrogen sulfide gas has a distinctive rotten egg odor that can be detected by most people at relatively low concentrations. Do not rely on your sense of smell, however, to determine if hydrogen sulfide levels are safe. Olfactory fatigue can deaden your sense of smell over time and at high concentrations.

References

• Occupational Health & Safety: Human Health Effects from Exposure to Low-Level Concentrations of Hydrogen Sulfide
• OSHA Fact Sheet: Hydrogen Sulfide
• OSHA Chemical Sampling Information: Hydrogen Sulfide

Resources

• Read this Article in Spanish
• EPA: National Service Center for Environmental Publications (NSCEP)