WorkSafe BC Part 31 - Respirators states:
Firefighters who may be exposed to an oxygen deficient atmosphere or to harmful concentrations of air contaminants must wear a self-contained breathing apparatus of a positive pressure type having a rated minimum duration of 30 minutes.
At one of the Phoenix Fire Department's Health, Fitness and Safety Symposium they had a workshop that discussed the use of Self-contained Breathing Apparatus during overhaul operations. Some of the questions asked were: When do we remove our SCBA? Who makes that decision? Usually it is the incident commander with advice from the incident scene safety officer who will give the green light 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.
Our Drager gas monitors can only measure CO, O2, LEL and H2S. 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.” Yes firefighters can work easier without the cumbersome SCBA, however is it really healthier?
Phoenix also found out that waiting about 30 minutes and letting the area air out, as you might expect, reduces the chemicals. We currently use our gas-powered blowers to ventilate however, the blower produces about 39 ppm of carbon monoxide. After using the gas-powered blower, the electric smoke fan from Truck Company should be considered. The acceptable WorkSafe BC level for working in an atmosphere with carbon monoxide is 25 ppm (TWA).
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.
Structural Fire Overhaul - Respiratory Hazards and Personal Protective Equipment.pdf
CHARACTERIZATION OF FIREFIGHTER EXPOSURES DURING FIRE OVERHAUL (Phoenix Study).pdf
Mandatory SCBA Usage During Smoke Exposures.pdf