CARBON-MONOXIDE AND WATER-VAPOR CONTAMINATION OF COMPRESSED BREATHINGAIR FOR FIREFIGHTERS AND DIVERS

Compressed breathing air, used in self-contained breathing apparatus ( SCBA) by firefighters and other categories of workers as well as by re creational and commercial divers, is prepared with the aid of high-pre ssure compressors operating in the range of 5000 psig. There have been reports of unexplained deaths of SCUBA divers and anecdotal accounts of decreased time to exhaustion in firefighters using SCBAs. Compresse d breathing air has been found to contain elevated levels of carbon mo noxide (GO) and water vapor that are consistent with carboxyhemoglobin (COHb) poisoning and freezing of the user's regulator on the breathin g apparatus. The Coburn-Forster-Kane equation (CFK equation) was used to estimate COHb levels at rest and at maximum exercise when exposed t o different levels of CO in contaminated breathing air. The results de monstrated that, at maximum exercise, the COHb ranged from 6.0 to 17% with the else of 1 to 4 SCBA cylinders contaminated by 250 ppm CO. Sta ndard operating procedures have been developed at the Montreal Fire De partment to minimize the risk of compressed breathing air contaminatio n. Results of the quality analysis/quality control program indicate th at implementation of these procedures has improved the quality of the compressed breathing air. Recommendations are made for improvement of the air resting procedures mandated by the Canadian CAN3 180.1-M85 Sta ndard on Compressed Breathing Air and Systems.