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 Permissible Exposure Limits (PEL) for H2S are listed below for conditions stated:
General industry - up to 20 ppm.
Exceptions - may exceed 20 ppm if no other exposures during 8 hour work shift, but not more than 50 ppm for a single time exposure for 10 minutes.
Construction industry - up to 10 ppm
Maritime industry - 10 ppm
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) - 1 ppm and for Short Term Exposure Limit (STEL) 5 ppm National Institute for Occupational Safety and Health (NIOSH)
Recommended Exposure Limit (REL) - 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.