Use of Self-contained Breathing Apparatus During Overhaul
As a representative of Local 230 on the San Jose Fire Department Safety Committee, I recently attended the Phoenix Fire Department Health, Fitness and Safety Symposium. One of the workshops discussed the use of Self-contained Breathing Apparatus during overhaul operations. When do we remove our SCBA? Who makes that decision? Usually it is the incident commander. Advice from the incident scene safety officer may also be the criteria for operating in an atmosphere without the use of the SCBA.
Previous studies have characterized firefighter exposures during fire suppression. However, minimal information is available regarding firefighter exposures during overhaul and checking for extension. Firefighters, often without respiratory protection, look for hidden fire inside attics, ceilings and walls and perform overhaul operations.
A comprehensive air monitoring study was conducted by Phoenix Fire Department to characterize firefighter exposures during the overhaul phase of 25 structure fires. Personal samples were collected for aldehydes, benzene, toluene, ethyl benzene, xylene, hydrochloric acid, polynuclear aromatic hydrocarbons, respirable dust and hydrogen cyanide. Gas analyzers were employed to continuously monitor carbon monoxide, hydrogen cyanide, nitrogen dioxide and sulfur dioxide. Area samples were collected for asbestos, metals and total dust.
During overhaul, the following exceeded published ceiling values: acrolein (ACGIH 0.1 ppm) at one fire; carbon monoxide (NIOSH 200 ppm) at five fires; formaldehyde ( NIOSH 1ppm) at two fires, nitrogen dioxide (NIOSH 1 ppm) at two fires and sulfur dioxide(ACGIH 5 ppm) at five fires. On an additive effects basis, aromatic hydrocarbon concentrations exceeded the NIOSH REL (0.1 mg/M3) for coal tar pitch volatiles at two fires. Maximum concentrations of other sampled substances were below their respective published exposure limits. Initial 10-minute average carbon monoxide concentrations did not predict concentrations of other products of combustion.
The results indicate that firefighters should use respiratory protection during overhaul. In addition, these findings suggest that carbon monoxide should not be used as an indicator gas for other contaminants found in this atmosphere.
San Jose Fire Department has used our HIT and USAR companies to take samples of air during the overhaul stage at a fire; however, HIT and USAR units can only measure carbon monoxide. The above description of what Phoenix has found out regarding the products of combustion indicates we should examine closely when it is acceptable to “get rid of the SCBA.” Firefighters can work easier without the cumbersome SCBA. Is it really healthier?
Phoenix also found out waiting about 30 minutes and letting the area air out, as you might expect, reduces the chemicals. We often use gas-powered smoke blowers to help us; however, the blower produces about 39 ppm of carbon monoxide. After using the gas-powered blower, the electric smoke fan should be considered. The acceptable Cal-OSHA level for working in an atmosphere with carbon monoxide is 50 ppm. This has been used in the past as a guide to remove the SCBA and go to dust masks. Additionally applying a foam blanket to the burned area reduces the off-gassing of the chemicals mentioned.
As firefighters, we can reduce our exposures by wearing SCBA’s for the entire overhaul period. Yes, it is harder to work with the SCBA on our back; however, it is healthier. We can do things to make it somewhat easier. We can lesson the load by wearing our wildland jackets with the SCBA or we can relieve crews more frequently.
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