Physiological responses to design adaptations in firefighting PPC during simulated firefighting tasks

Introduction. To ameliorate the effects of steam and chemical ingress during firefighting operations, modern Personal Protective Clothing (PPC) require the presence of a moisture barrier. Little research has been undertaken evaluating the impact of this barrier on physiology of firefighters working in different environments. Methods. Ten Australian recruit firefighters (5 per group), (mean ±SD age 30.8 ± 5.8 years), undertook one of two 20 minute simulated firefighting tasks separated by a 10 minute recovery period; 1) In a heat chamber set at 120 °C, filled with smoke, firefighters conducted a search and rescue task 2) At ambient temperatures (17 °C), firefighters completed firefighting activities. After the recovery period, the task was repeated. A randomised order crossover design saw participants wearing PPC containing either a moisture barrier (BARR) or no moisture barrier (NBAR). Results. Relative to NBAR (37.7 ± 0.7 °C) BARR showed a moderate increase in core temperatures (38.0 ± 0.5 °C, η²=0.096) and a small increase in air consumption (NBAR 64.5 ± 8.3 L.min^-1, BARR 66.6 ± 1.9 L.min^-1, η²=0.037) in the ambient condition group. No meaningful differences for skin temperature or change in body mass were observed. Compared with NBAR (39.0 ± 0.6 °C), BARR resulted in higher skin temperatures (39.6 ± 0.6 °C, η²=0.178) and greater air consumption (NBAR 45.8 ± 7.5 L.min^-1, BARR 48.7 L.min^-1 ± 7.1, η²=0.044) and a greater change in body mass (NBAR 2.4 ± 0.6 %, BARR 2.6 ± 0.9 %, η²=0.021) in the heat chamber. No differences for core temperatures were observed in the heat chamber group. Conclusion. The presence of a moisture barrier in structural firefighting PPC may be increasing thermal stress encountered in firefighting settings. Increased strain resulting from design changes may require re-evaluation of work practices to account for the stress of wearing structural PPC when responding to emergencies.