Keywords:  twa, tlv, worker, eight, exposure
concentration for a normal 8-hour working day (40 hours/week) to which all workers may be exposed without adverse effect.
(TLV-TWA, Threshold Limit Value-Time Weighted Average) The time weighted average airborne chemical concentration for a normal eight hour work day and a 40 hour work week to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.
An exposure limit averaged over eight hours that must not be exceeded during an employee's workday.