Abstract
Overhaul is the phase of firefighting after flames have been extinguished but when products of combustion are still being released. While positive pressure self-contained breathing apparatus (SCBA) provide the highest level of respiratory protection during overhaul, use of air-purifying respirators (APRs) with suitable filters could potentially provide a lower weight, longer duration option for first responders. The objective of this study was to assess whether an APR with a chemical, biological, radiological, and nuclear (CBRN) canister could be recommended as substitution for SCBA during overhaul. A total of 15 simulated standard overhaul environments were created by burning household materials. Sampling was conducted using mannequin heads fitted with full facepiece respirators with either a CBRN canister or SCBA. In-mask and personal samples were collected for aldehydes, polynuclear aromatic hydrocarbons, inorganic acids, aromatic hydrocarbons, nitrogen dioxide, and particulate matter. An additional six simulated high-exposure overhaul environments were created in a flashover chamber by continuously adding household materials to a smoldering fire. The sampling train was the same for both the standard and high-exposure environments; however, the facepiece was sealed to the mannequin head in the high-exposure environments. In the standard overhaul environment, the CBRN canister effectively reduced the level of exposure for most contaminants, while in the high-exposure overhaul exposure setting in-mask acetaldehyde and formaldehyde were detected. In both exposure settings, the SCBA prevented almost all exposure, and therefore remains the recommended respiratory protection during overhaul.