Thermal-work strain in law enforcement personnel during chemical, biological, radiological, and nuclear (CBRN) training

BACKGROUND: Thermal safety standards for the use of chemical, biological, radiological, and nuclear (CBRN) ensembles have been established for various US occupations, but not for law enforcement personnel. OBJECTIVES: We examined thermal strain levels of 30 male US law enforcement personnel who participated in CBRN field training in Arizona, Florida, and Massachusetts. METHODS: Physiological responses were examined using unobtrusive heart rate (HR) monitors and a simple thermoregulatory model to predict core temperature (T(c)) using HR and environment. RESULTS: Thermal strain levels varied by environments, activity levels, and type of CBRN ensemble. Arizona and Florida volunteers working in hot-dry and hot-humid environment indicated high heat strain (predicted max T(c)>38.5°C). The cool environment of Massachusetts reduced thermal strain although thermal strains were occasionally moderate. CONCLUSIONS: The non-invasive method of using physiological monitoring and thermoregulatory modeling could improve law enforcement mission to reduce the risk of heat illness or injury.