Wildland Firefighter Helmet Air-Supply System for Reducing Smoke Exposure and Heat Stress

Abstract: The scope and severity of wildfires worldwide have increased during the past several decades. Thousands of firefighters are employed each year to control these fires. The occupational health and safety risks associated with wildland firefighting are significant and numerous. The most common are physical injury, smoke inhalation and heat stress. A prototype helmet air supply system was developed to reduce such risks. The system uses air ducts inside the helmet that channel filtered air to the breathing zone and filtered air over the head of the firefighter. The system was designed to provide a comfortable, discreet, and simple solution for reducing occupational exposure to smoke and heat stress while providing an alternative to the respiratory and heat stress protection options currently available. Methods and Procedures:Airflow for the helmet air supply tubing was evaluated using a digital precision thermoanemometer probe. Air velocity measurements were based on three-minute sampling periods where the digital thermoanemometer recorded air velocities every second for a total of 180 individual measurements. To determine the airflow reaching the breathing zone, the tubing for head cooling was blocked. To determine the airflow for head cooling only, the tubing to the breathing zone was blocked. To determine the combined airflow to both the breathing zone and head cooling, all tubes remained open. To assess the sweat evaporation potential from the head, a thermal manikin head equipped with multiple skull thermocouple probes and including a sweat evaporation liner were used.Results:The data showed that the system provided a combined positive pressure airflow into the helmet of 400 l/min for both the firefighter’s breathing zone and the head. This air volume for the breathing zone is high enough so that a face shield is not needed to provide protection against an incursion of fire smoke into the breathing zone. The thermocouple data showed that the airflow over the head increased the scalp sweat evaporation by 35% in comparison to not wearing a helmet. The system is compatible with all current firefighter protective equipment safety and performance requirements. Additionally, the unit is intended to operate on batteries that are used in standard firefighting communication equipment. Conclusions:The development and testing of the prototype system have shown the potential for improving the health and safety of wildland firefighters in the future. Although the tests were conducted inside a controlled laboratory environment, the fundamental principle of providing fresh air to a firefighters' breathing zone thereby displacing smoke, while also reducing heat stress, appears feasible. The demand for wildland firefighter personnel is increasing throughout the world. Therefore, providing better respiratory protection and improved heat stress management is a common-sense solution. Applications of this technology to other occupations in the future such as construction work and industrial work will be possible.

Keywords: Wildland firefighters, smoke exposure, heat stress, protopye helmet air supply system

DOI: 10.54941/ahfe1006582

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