TLV and STEL are both occupational exposure limits related to workplace safety. However, the provided reference only defines STEL. Therefore, this answer will focus on defining STEL based on the reference, and give a general explanation of TLV.
STEL, or Short-Term Exposure Limit, is a 15-minute time-weighted average exposure that should not be exceeded at any time during a workday, even if the overall time-weighted average exposure for the day is within the Threshold Limit Value (TLV). (TLV-STEL)
In simpler terms, STEL is a limit on how much of a substance a worker can be exposed to in any 15-minute period during their workday.
- It's designed to prevent immediate adverse health effects from short, high-intensity exposures.
- The TLV sets a long-term exposure limit, while the STEL provides a short-term safety net.
TLV, or Threshold Limit Value, refers to the concentration of a substance in the air to which it is believed that workers can be exposed daily during their working lifetime without adverse health effects.
Here's a table summarizing the key differences:
| Feature | STEL | TLV |
|---|---|---|
| Definition | 15-minute time-weighted average exposure limit. | Concentration to which workers can be exposed daily without adverse health effects. |
| Timeframe | Short-term (15 minutes) | Long-term (daily over a working lifetime) |
| Purpose | Prevent immediate adverse health effects from short, high-intensity exposures. | Protect workers from long-term health effects associated with chronic exposure. |
| Exceedance Rule | Must not be exceeded at any time during a workday, even if the daily TLV is met. (TLV-STEL) | Designed as a guideline to be met over the long term, though exceeding it isn't recommended and should be minimized. |
