Extreme occupational heat exposure is associated with elevated haematological and inflammatory markers in Fire Service Instructors

Emily R. Watkins, Mark Hayes, Peter W. Watt, Derek Renshaw, Alan J. Richardson

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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.

© 2020, The Physiological Society. The attached document (embargoed until 27/05/2021) is an author produced version of a paper published in EXPERIMENTAL PHYSIOLOGY uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it.

Original languageEnglish
Number of pages11
Early online date27 May 2020
Publication statusE-pub ahead of print - 27 May 2020

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