n the past, the most widely recognized occupational exposure limits for hydrogen sulfide (H2S) have referenced an 8-hour TWA of 10 ppm, and a 15-minute STEL of 15 ppm. In February 2010, the American Conference of Governmental Industrial Hygienists (ACGIH®) adopted a new threshold limit value (TLV®) recommendation for H2S, lowering the 8-hour TWA to 1.0 ppm, and the STEL to 5.0 ppm. The new TLV® has forced many companies to reconsider exposure limit guidelines and alarm settings. A major issue is whether a company’s current instruments are capable of operation with alarms set to the new 1.0 ppm limit. Employers may need to verify whether or not this is possible with a particular instrument design.
How dangerous is H2S?
Hydrogen sulfide is a colorless gas that at low concentrations has an odor similar to rotten eggs. At higher concentrations, H2S rapidly deadens the sense of smell. For most people, a concentration of 150 ppm is enough to immediately deaden the sense of smell. At a concentration of about 750 ppm or higher, inhalation of H2S can cause immediate collapse and unconsciousness. A single breath at a concentration of 1,000 ppm results in immediate loss of consciousness, followed by cardiac arrest and death unless the unconscious individual is successfully revived. |
| STAY AWAY FROM THE EXPOSURE AREA WITH THESE SIGNAGE |
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| VICTIM OF HYDROGEN SULFIDE GETTING UNCONCIOUSNESS |
