Carbon Monoxide and Water Vapor Contamination of Compressed Breathing Air for Firefighters and Divers

Abstract

Compressed breathing air, used in self-contained breathing apparatus (SCBA) by firefighters and other categories of workers as well as by recreational and commercial divers, is p r e pared with the aid of high-pressure 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. Compressed breathing air has been found to contain elevated levels of carbon monoxide (CO) and water vapor that are consistent with carboxyhemoglobin (COHb) poisoning and freezing of the user's regulator on the breathing apparatus. The Coburn-Fonter-Kane equation (CFK equation) was used to estimate COHb levels at rest and at maximum exercise when exposed to different levels of CO in contaminated breathing air. The results demonstrated that, at maximum exercise, the COHb ranged from 6.0 to 17% with the use of 1 to 4 SCBA cylinders contaminated by 250 ppm CO. Standard operating procedures have been developed at the Montreal Fire Department to minimize the risk of compressed breathing air contamination. Results of the quality analysis/quality control program indicate that implementation of these procedures has improved the quality of the compressed breathing air. Recommendations are made for improvement of the air testing procedures mandated by the Canadian CAN3 180.1-Ma5 Standard on Compressed Breathing Air and Systems.

Headache in Divers

“…Headache is an early symptom of poisoning from carbon monoxide (CO), which rarely can contaminate the diver's compressed air supply if the air intake system is positioned so as to gather improperly directed combustion engine exhaust 54‐57 . Binding to hemoglobin with 250‐fold greater affinity than oxygen, CO compromises the oxygen‐carrying capacity of hemoglobin.…”

Fire Fighters, Combustion Products, and Urothelial Cancer

“…Most of the published articles concerning the toxicology of combustion products deal with the role of a limited number of inorganic compounds such as carbon monoxide (CO), carbon dioxide (CO 2 ), hydrogen cyanide (HCN), hydrochloric acid and other halogen acids, and nitrogen oxides (Hartzell, 1996). It should be noted that some cases of adverse health problems due to carbon monoxidecontaminated compressed air were reported in divers and fire fighters (Austin et al, 1997).…”

Headache and facial pain in scuba divers

“…Headache also is an early symptom of poisoning from carbon monoxide (CO), an odorless gas that rarely has contaminated a diver's compressed air supply when, during tank preparation, the air intake system was inadvertently positioned toward street traffic and exposed to the combustion engine exhaust of an idling vehicle [25][26][27]. Binding to hemoglobin with 250-fold greater affinity than oxygen, CO impairs the oxygen-carrying capacity of hemoglobin.…”