Threshold Limit Value-Time Weighted Average (TLV-TWA) is the time-weighted average concentration for a normal 8-hour workday and 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.

• 阈值极限-时间权重平均值(TLV-TWA)是对于正常的8小时工作日和40小时工作周的时间权重平均值，在该值下，大多数工人日复一日的重复暴露在其中而不会受到有害影响。