Fire Service Instructors (FSI) experience ~10 times more fire exposures than firefighters (FF), the increased physiological stress from this potentially puts them at risk of ill health and future cardiac events. This study aimed to establish whether FSI exhibit elevated biomarkers associated with cardiac event risk, identify if FSI experience systemic inflammation linked to fire exposure frequencies and evaluate a proposed exposure limit of 9 per month. Blood samples were collected from 110 Fire Service personnel (age: 44 ± 7 yrs; height: 178.1 ± 7.1 cm; body mass: 84.3 ± 12.0 kg, FSI n = 53, FF n = 57) for biomarker analysis. Work history details were collected from all participants. Participants with biomarker concentrations above healthy reference ranges were classified as “at risk”. Neutrophil/lymphocyte ratio, platelet count, cardiac troponin T, interleukin-6 (IL-6), interleukin-1β (IL-1β), immunoglobulin G (IgG) and C reactive protein (CRP) were greater in FSI than FF (p<0.05). Multiple regression analysis revealed 18.8% of IL-6, 24.9% of IL-1β, 29.2% of CRP, and 10.9% of IgG variance could be explained by number of heat exposures per month. Odds ratios revealed that those above the 9 per month exposure limit were 6-12 times more likely to be classified as “at risk” and were 16 times more likely to experience symptoms of ill health. Increased cytokine levels suggest FSI experience systemic inflammation, which is related to symptoms of ill health. We propose that an exposure limit could reduce the prevalence of these biomarker risk factors and ill health.
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