Heat Strain In A Small Sample Of Road Construction Workers During The Summer

Road construction workers perform physically demanding jobs, including building frames, laying concrete and asphalt, and operating heavy machinery. These activities may result in high metabolic heat production. When combined with high environmental heat exposure during warmer periods of the year, road construction workers may experience substantial heat strain, making them susceptible to heat-related illnesses. Despite the heat-related risks, no studies have assessed heat strain on road construction workers during the summer. PURPOSE: To quantify physiological heat strain and environmental heat stress in road construction workers during a typical workday in the southwest United States in the summer. METHODS: Seven male road construction workers (age = 39 ± 14 years, body weight = 86.1 ± 25.4 kg, height = 170 ± 5 cm, body mass index = 29.9 ± 8.9 kg/m2) were monitored for markers of heat strain during a typical workday in the summer. The job tasks required pouring concrete and performing general cleaning during bridge construction and repair. Core (Tc) and skin (Ts) temperatures were continuously monitored throughout the day using an ingestible telemetric capsule and wireless skin sensors, respectively. Hydration was assessed by urine specific gravity (USG) and changes in body weight from pre- to post-work shift. Heat index (HI) was calculated from continuous dry bulb temperature and humidity measurements for the duration of the workday. RESULTS: The average peak Tc was 37.89 ± 0.16 °C, and 2 of the 7 workers (29%) reached a peak core temperature of greater than 38.0 °C. Peak values for skin temperature were 36.71 ± 0.62 °C, with average values being 34.21 ± 1.43 °C. The average heat index was 24.5 °C (min: 18.1 °C, max: 34.1 °C), with an average dry bulb temperature of 26.3 °C (min: 19.8 °C, max: 36.1 °C). There were no significant changes in USG from pre- (1.021 ± 0.011) to post-shift (1.024 ± 0.008) (p = 0.30). Notably, 4 out of 7 (57%) workers started the day in a dehydrated state (USG > 1.020). Body weight decreased from pre- (86.1 ± 25.3 kg) to post-work (85.3 ± 25.2 kg) (p = 0.02) resulting in a loss of 0.85 ± 1.0%. There was a moderate, positive correlation between heat index and core temperature (p = 0.001, r = 0.62) CONCLUSION: Road construction workers experience moderate heat strain while working in hot dry conditions in the summer. This study was supported by CPWR (#22-5-PS) and NIOSH (R01OH011528).