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Firefighters are occupationally exposed to many chemicals, including polycyclic aromatic hydrocarbons (PAHs), which are formed by the incomplete combustion of organic matter during fire response and training activities. However, due to the harsh environments in which firefighters work, as well as consideration for time and physical safety while wearing bulky equipment, traditional active sampling methods may not be feasible to measure PAH exposures. Silicone passive samplers offer an alternative approach to assess exposure during fire responses and live fire training due to their heat resistance and ease of deployment in remote or time-limited environments. In this study, the primary objective was to investigate and determine the statistical strength of the relationship between active air sampling methods and passive silicone samplers for PAHs. In this study, silicone wristbands were paired with active sampling devices in a series of burn experiments to compare PAH measurements. Silicone-based measurements correlated strongly with active air samples for the dominant PAHs found, naphthalene and phenanthrene; however, detection was limited in the wristbands when air concentrations were low in active samples. In situations where PAH levels are expected to be high and the potential for contaminant loss via off-gassing is low, silicone samplers may be a useful tool for industrial hygienists to measure PAHs in fire and other emergency responses in extreme environments.

Firefighters' or instructors' exposure to airborne chemicals during live-fire training may depend on fuels being burned, fuel orientation and participants' location within the structure. This study was designed to evaluate the impact of different control measures on exposure risk to combustion byproducts during fire dynamics training where fuel packages are mounted at or near the ceiling. These measures included substitution of training fuels (low density wood fiberboard, oriented strand board (OSB), pallets, particle board, plywood) and adoption of engineering controls such as changing the location of the instructor and students using the structure. Experiments were conducted for two different training durations: the typical six ventilation cycle (6-cycle) and a shorter three ventilation cycle (3-cycle) with a subset of training fuels. In Part A of this series, we characterized the fire dynamics within the structure, including the ability of each fuel to provide an environment that achieves the training objectives. Here, in Part B, airborne chemical concentrations are reported at the location where fire instructors would typically be operating. We hypothesized that utilizing a training fuel package with solid wood pallets would result in lower concentrations of airborne contaminants at the rear instructor location than wood-based sheet products containing additional resins and/or waxes. In the 6-cycle experiments (at the rear instructor location), OSB-fueled fires produced the highest median concentrations of benzene and 1,3 butadiene, plywood-fueled fires produced the highest total polycyclic aromatic hydrocarbon (PAH) concentrations, particle board-fueled fires produced the highest methyl isocyanate concentrations, and pallet-fueled fires produced the highest hydrogen chloride concentrations. All fuels other than particle board produced similarly high levels of formaldehyde at the rear instructor location. The OSB fuel package created the most consistent fire dynamics over 6-cycles, while fiberboard resulted in consistent fire dynamics only for the first three cycles. In the follow-on 3-cycle experiment, PAH, benzene, and aldehyde concentrations were similar for the OSB and fiberboard-fueled fires. Air sampling did not identify any clear differences between training fires from burning solid wood pallets and those that incorporate wood-based sheet products for this commonly employed fuel arrangement with fuels mounted high in the compartment . However, it was found that exposure can be reduced by moving firefighters and instructors lower in the compartment and/or by moving the instructor in charge of ventilation from the rear of the structure (where highest concentrations were consistently measured) to an outside position., Competing Interests: Conflict of interest. There are no conflicts of interest regarding this work. The findings and conclusions are those of the author(s) and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.

The fire modeling community currently lacks full-scale experi- mental data from fires in residential-style structures with heat- ing, ventilation, and air conditioning (HVAC) systems. Further, there is an absence of data quantifying the generation of H 2 O due to combustion and the subsequent transport of those gases with a structure. Propane gas burner fire experiments were con- ducted in a purpose-built two-story structure instrumented to measure temperature, pressure, velocity, and gas concentrations. Experiments were conducted to assess heat and gas species trans- fer due to HVAC operating status (off vs. on), fire location and heat release rate, and bedroom door position (open vs. closed)., Competing Interests: The authors declare that they have no known competing financial interests or personal relation- ships which have, or could be perceived to have, influenced the work reported in this article., (© 2022 The Author(s).)

The fire modeling community currently lacks full-scale data from tests conducted in realistic residential-style structures. Controlled gas burner tests were conducted in purpose-built single- and two-story structures instrumented throughout with thermocouples, pressure transducers, and bi-directional probes. Experiments consisted of sequences of ventilation events. The data collected in these tests was intended to provide several new validation cases for the fire modeling community., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article., (© 2021 The Author(s). Published by Elsevier Inc.)