AL and PEL are expressed in ug/m3 and are based on which time period?

AL and PEL are expressed in ug/m3 and are based on which time period?

• A. 1-hour Peak
• B. 24-hour Average
• C. 8-hour Time Weighted Average
• D. 30-minute Average

Answer: (C)

Lead exposure limits are defined as an eight-hour time-weighted average. This means the concentration of lead in the air is averaged over an eight-hour work shift, weighting the exposure by how long a worker is exposed at each level. The AL triggers monitoring and certain actions, and the PEL is the maximum permissible average over that same eight-hour period. Short-term spikes or shorter time frames aren’t used to set these limits, so an 8-hour average, not a 1-hour peak, 30-minute, or 24-hour value, is the basis.

Lead exposure limits are defined as an eight-hour time-weighted average. This means the concentration of lead in the air is averaged over an eight-hour work shift, weighting the exposure by how long a worker is exposed at each level. The AL triggers monitoring and certain actions, and the PEL is the maximum permissible average over that same eight-hour period. Short-term spikes or shorter time frames aren’t used to set these limits, so an 8-hour average, not a 1-hour peak, 30-minute, or 24-hour value, is the basis.