What Does Short-Term Exposure Limit (STEL) Mean?
The short-term exposure limit (STEL) is defined as the average concentration of a substance that personnel can be safely subjected to continuously over a 15-minute time-weighted average. Individuals exposed to substances with concentrations less than the STEL within the 15-minute time-weighted average can withstand exposure without a risk of:
- Long-term tissue damage
- Narcosis to a degree that increases the likelihood of accidental injury
Knowing the short-term exposure limit is important for the safety of personal working near potentially hazardous substances.
Corrosionpedia Explains Short-Term Exposure Limit (STEL)
Short-term exposure limits are generally stated when substances are likely to cause short-term acute effects in humans. As such, STELs are not separate exposure limits; instead, they supplement time-weighted average limits (TLV-TWA).
While STEL values limit the exposure of workers in a 15-minute period, persons should not be exposed to STEL concentrations for more than four times per day. Additionally, there should be at least a 60-minute interval between exposures.
STEL limits are quoted for several chemical compounds and are expressed in milligrams per meter cubed (mg/m3) or parts per million (ppm). These parameters are enforced in the United States by the Occupational Safety and Health Administration (OSHA). The American Conference of Governmental Industrial Hygienists (ACGIH) also publishes an extensive list of STEL values for numerous chemicals.