Environment, health and safety

In managing chemical exposure, which limit is set for short exposures such as 15 minutes, separately from the 8-hour average value?

  1. ALower explosive limit (LEL)
  2. BShort-term exposure limit (STEL)
  3. CFlash point
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Answer: B. Short-term exposure limit (STEL)

Even if the 8-hour time-weighted average is within the standard, brief exposure to high concentrations can cause irritation or acute poisoning. The short-term exposure limit (STEL) is an upper limit on concentration averaged over, for example, 15 minutes, and for some substances a ceiling value that must not be exceeded even momentarily is also set.

  • A. The LEL is the lowest concentration that can burn or explode.
  • B. Correct. It is the upper limit for short-term exposure.
  • C. The flash point is the lowest temperature at which a liquid's vapor can ignite.
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