Negligible heat strain in armored vehicle officers wearing personal body armor

Twelve male AVOs, aged 35-58 years, undertook an eight hour shift while wearing PBA. Heart rate and core temperature were monitored continuously. Urine specific gravity (USG) was measured before and after, and with any urination during the shift.Heart rate indicated an intermittent and low-intensity nature of the work. USG revealed six AVOs were dehydrated from pre through post shift, and two others became dehydrated. Core temperature averaged 37.4 ± 0.3°C, with maximum's of 37.7 ± 0.2°C.Despite increased age, body mass, and poor hydration practices, and Wet-Bulb Globe Temperatures in excess of 30°C; the intermittent nature and low intensity of the work prevented excessive heat strain from developing.The human body requires a relatively constant core body temperature to function effectively. In order to maintain a stable temperature, the body must continually lose heat to the surrounding environment at the same rate as heat is produced. Several factors influence the capacity for heat exchange to meet the required rate; these include environmental factors (air temperature, wind speed, relative humidity, and radiant heat), metabolic rate, and clothing. In certain occupations the clothing that an individual is required to wear takes on a protective role. These clothing ensembles are generally very effective at preventing injury when a specific hazard is encountered, however, the added weight of the clothing, and its effect on the transfer of body heat to the environment, can significantly increase the heat strain experienced by the wearer [1].Cash in transit security guards, also known as armored vehicle officers (AVOs), are increasingly being required to wear ballistic protection or personal body armor (PBA). A number of cash in transit companies have introduced these mandatory policies in response to fatalities in the industry. The function of the PBA is to protect the wearer from physical harm if a hostile situation is encountered. In performing this vital role, the