APPENDIX B. Air Concentration Calculations for Comparison to OSHA Standards ~OSHA
***** {Calculation methods for air concentrations of gas in ppm"the OSHA PEL in mg/m3 is absolutely fixed and not subject to corrections for temperature and pressure." "This constraint implies that volume concentration of gases in parts per million (ppm) must be with reference to some defined temperature and pressure; these are NTP (25 °C and 760 mm Hg) in the OSHA PEL limit."