Occupational Health and Safety Act, 1993 (Act No. 85 of 1993)

Regulations

Regulations for Hazardous Chemical Agents, 2020

Annexures

Annexure 3 : Hazardous Chemical Agent Guidelines

Guidance on medical surveillance and biological monitoring

Mixed exposures

The 8-hour reference period
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88.The term "8-hour reference period" relates to the procedure whereby the occupational exposures in any 24-hour period are treated as equivalent to a single uniform exposure for eight hours [the 8-hour time weighted average (TWA) exposure].

 

The eight-hour TWA may be represented mathematically by:

 

R280 Annex 3 (88) (2)

 

 

where C1 is the occupational exposure value (concentration) and T1 is the associated exposure time in hours in any 24-hour period.