Posted by proforma on July 5, 2011 | No Comments
OSHA doesn’t say that an oxygen level of 19.5 percent is “safe”; it says that levels below 19.5 percent may be hazardous. Do your workers understand why 19.5 percent is significant?
As this article points out, 19.5 percent oxygen was selected based on the adverse physiological effects that can appear at an oxygen partial pressure less than 148 mm Hg. Moisture and other gases play a significant role, however. Even if the oxygen available is higher than 19.5 percent, there may be hazardous concentrations of other gases and vapors. Some gases and vapors may be present at concentrations well above the TLV while, at the same time, they are below a combustible gas meter’s limit of detection.
Believing that 19.5 percent is “safe” has lead to deaths when entering an oxygen-deficient atmosphere, including the safety officer performing the test. The entry supervisor had not realized that although the oxygen level at 20.1 percent was insufficient. Find out why.