Special precautions: Be aware of any signs of dizziness or fatigue; exposures to fatal concentrations of Hydrogen Sulfide could occur without any significant warning symptoms. All work operations should be monitored in such a way that emergency personnel can be immediately contacted in the event of a release. All work practices should minimize the release of Hydrogen Sulfide.
It should be noted that the effects from exposure to Hydrogen Sulfide will depend on several factors including: frequency and duration of use; quantity used; effectiveness of control measures; protective equipment used and method of application. Given that it is impractical to prepare a Chem. Alert report which would encompass all possible scenarios, it is anticipated that users will assess the risks and apply control methods where appropriate.
H2S exposure limits
PEL =20 ppm (Ceiling) , (10 minutes)
TWA =10 ppm ; STEL =15 ppm
REL =10 ppm (Ceiling) ; IDLH = 100 ppm
Avoiding exposure to hydrogen sulfide is the best way to protect health. Options that should be considered include the use of the following (in order of preference):
- engineering controls
- administrative controls
- personal protective equipment
Engineering controls are used to eliminate exposure to a substance. Engineering controls remove the substance from the air or provide a barrier between the worker and the substance. Examples of engineering controls that can be used to prevent exposure to hydrogen sulfide include the use of:
Ventilation to control hydrogen sulfide concentrations in the air
Closed systems that vent to a flare, and
Treatment methods to remove hydrogen sulfide from liquid and gas streams.
Personal protective equipment
Since hydrogen sulfide is irritating to the eyes, air-tight goggles or full-face respirator masks should be worn.
A full-face piece positive pressure supplied air respirator is needed for work areas where hydrogen sulfide concentrations exceed the OEL. The National Institute for Occupational Safety and Health (NIOSH) specifies an IDLH (immediately dangerous to life or health) concentration for hydrogen sulfide of 100 ppm. NIOSH allows the use of air purifying respirators for hydrogen sulfide only for escape purposes at concentrations below the IDLH concentration. Above the IDLH concentrations, or for emergency or planned entry into unknown concentrations, a full-face piece positive pressure supplied air respirator must be used. Whatever the type of respirator used, the worker must be clean-shaven where it seals to the skin of the face and must be fit-tested for the type of equipment being used.