If an employee is exposed to lead for more than 8 hours in any work day the employees' allowable exposure, as a Time Weighted Average (TWA) for that day, shall be reduced according to the following formula:
Allowable employee exposure (in ug/m(3)) = 400 divided by hours worked in the day.
When respirators are used to limit employee exposure as required under 29 CFR 1926.62 paragraph (c) and all the requirements of paragraphs (e)(1) and (f) have been met, employee exposure may be considered to be at the level provided by the protection factor of the respirator for those periods the respirator is worn.
Those periods may be averaged with exposure levels during periods when respirators are not worn to determine the employee's daily TWA exposure.
