What Does H2S Exposure Limits Mean?
H2S (Hydrogen Sulfide) is a highly toxic gas that can kill or seriously harm human health when exposed to it, even at low concentrations like 10 parts per million (ppm). H2S is normally found in the oil and gas fields (well drilling, servicing, work over, down hole maintenance, plug and abandonment procedures etc.) or in the storage tanks and transports of such substances that releases H2S.
Safeopedia Explains H2S Exposure Limits
OSHA's Worker Exposure Limits for H2S are as follows:
- General Industry Ceiling Limit: 20 ppm
- General Industry Peak Limit: 50 ppm
- Construction 8-Hour Limit: 10 ppm
- Shipyard 8-Hour Limit: 10 ppm
The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) is 1 ppm.
The National Institute for Occupational Safety and Health (NIOSH) sets the Short Term Exposure Limit (STEL) at 5 ppm.
The Recommended Exposure Limit (REL), also set by NIOSH, is at 10 ppm (10 Minutes).
H2S exposure can be monitored by the following instruments:
- Personal H2S monitor - worn by individuals, provides continuous monitoring and audible warning.
- Continuous fixed H2S monitoring systems - fixed at workplaces and used for continuous H2S concentration monitoring. It provides audible alarms.