How does OSHA measure oxygen availability for human respiration?
Reply (2): OSHA measures oxygen availability for human respiration using the percent of oxygen by volume in the workplace atmosphere. OSHA adopted this approach because it is the usual and customary practice among industrial-hygiene professionals to refer to oxygen-deficient atmospheres in terms of the percent of oxygen by volume. Also, in assessing oxygen levels in the workplace, employers often use hand-held meters that measure these levels, and the meters display this information as percent of oxygen by volume. By using terminology in the Standard that is consistent with these measurements, employers can determine immediately whether an atmosphere is safe for employee exposure. As a result, employers do not have to perform the additional step of calculating the oxygen partial pressure using a complex formula that, if not performed correctly, could have serious consequences for employees. OSHA recognizes that partial pressure of oxygen is the metric that reflects oxygen availability
