The Effect of Heat Stress on Cognition in Firefighters

Abstract

Firefighters are exposed to extreme heat and physical exertion while wearing insulating protective equipment, resulting in substantial heat stress. Deviances in cognitive functioning are critical for firefighter safety and performance, yet evidence on the cognitive effects of heat stress is largely investigated in non-firefighter populations. Due to training and repeated heat exposure, firefighters differ from the general population. Additionally, their work involves multiple stressors, which are rarely captured in laboratory studies. Therefore, these findings may not generalise to firefighting contexts.

A structured search was conducted using PubMed, Scopus, and Web of Science to identify peer-reviewed studies published between 2010 and 2025. Twenty-five studies were selected based on predefined inclusion criteria, requiring a defined heat exposure protocol and at least one objective cognitive outcome measure. Due to heterogeneity in study designs and outcomes, findings were synthesised narratively. Methodological quality was assessed using the Joanna Briggs Institute Critical Appraisal Tools.

Overall, evidence suggests that mild heat stress may facilitate simple cognitive processes, whereas prolonged or severe heat stress impairs cognitive performance. This commonly manifests as faster responses with reduced accuracy, indicating a speed–accuracy trade-off. These findings align with the Extended-U model, indicating a nonlinear, arousal-dependent relationship between heat stress and cognition, with impairment occurring once adaptive capacity is exceeded. Variability across studies is largely explained by methodological factors, including heat intensity, exposure duration, hydration status, task complexity, and timing of assessment.

Given the safety-critical nature of firefighting, future research should prioritise ecologically valid and longitudinal designs to better inform operational safety and recovery guidelines.