Section 325.77105. Exposure monitoring.

(1) Determinations of employee exposure shall be made from breathing zone air samples that are representative of each employee’s average exposure to airborne benzene.

(2)    Representative 8-hour TWA employee exposures shall be determined on the basis of 1 sample or samples representing the full shift exposures for each job classification in each work area.

(3)   Determinations of compliance with the short-term exposure limits (STEL) shall be made from 15-minute employee breathing zone samples that are measured at operations where there is reason to believe exposures are high, such as where tanks are opened, filled, unloaded, or gauged, where containers or process equipment are opened, and where benzene is used for cleaning or as a solvent in an uncontrolled situation. An employer may use objective data, such as measurements from brief period measuring devices, to determine where STEL monitoring is needed.

(4)    Except for initial monitoring required by R 325.77105a, if an employer can document that one shift will consistently have higher exposures for an operation, then the employer shall only be required to determine representative employee exposure for that operation during the shift on which the highest exposure is expected.

History: 1989 AACS; 2001 AACS; 2014 AACS.