Recently lowered exposure limit guidelines for H2S, SO2 and NO2 have forced many instrument users to revisit where to set the alarms in their atmospheric monitors. Exposure limits like the OSHA PEL, NIOSH REL and ACGIH® TLV® provide exposure limits, which if exceeded, may lead to immediate or long-term harm.
Workers should be out of the area before rather than after the concentration of toxic gas exceeds the hazardous condition threshold. Unfortunately, the PEL, REL and TLV® are not always in agreement.