What is the permissible exposure limit for exposure to Metal Working Fluids?
Currently two OSHA air contaminant permissible exposure limits apply to MWFs. They are 5 mg/m3 for an 8-hour time weighted average (TWA) for mineral oil mist, and 15 mg/m3 (8-hour TWA) for Particulates Not Otherwise Classified (PNOC) [applicable to all other metalworking fluids], 29 CFR 1910.1000. No other requirements exist. The American Conference of Governmental Hygienists (ACGIH) threshold limit value for mineral oils is 5 mg/m3 for an 8-hour TWA, and 10 mg/m3 for a 15-minute short-term exposure limit. In 1999, the OSHA Metalworking Fluids Standards Advisory Committee also recommended a new 8-hour time-weighted average permissible exposure limit of 0.4 mg/m3 thoracic particulate (0.5 mg/m3 total particulate). The committee based the recommended permissible exposure limit on studies of asthma and diminished lung function.
