Physical Work in Humid Heat Impairs Postural Balance during Simulated Construction Tasks at Height.

Purpose: Occupational heat strain can impair construction workers' motor and cognitive functions, potentially leading to accidents, injuries and lowered productivity. We examined the effects of physical work under various warm and humid tropical conditions on performance in virtual reality (VR)-based construction tasks.

Methods: Eighteen healthy men (age: 29 ± 5 years) completed three randomised, counterbalanced experimental trials comprising ~2.5 h of exposure to wet-bulb globe temperatures of 24.6 ± 0.2 °C (COOL), 28.1 ± 0.3 °C (WARM) and 32.4 ± 0.3 °C (HOT), representing Singapore's current (COOL and WARM) and projected (HOT) conditions. Participants performed three 30-min bouts of treadmill walking at fixed metabolic heat productions representing light (EX1: 250 W), moderate (EX2: 350 W) and heavy (EX3: 450 W) workloads, each separated by completion of a battery of VR-based construction tasks (welding and plank-walking at height). Task speed and accuracy, postural sway and gait were recorded during the VR tasks, while body core (Tc) and mean skin temperatures (Tsk), and heart rate (HR) were recorded continuously.

Results: Post-trial Tc was higher in HOT (38.6 ± 0.4 °C) compared with WARM (38.1 ± 0.3 °C; P < 0.001) and COOL (37.9 ± 0.3 °C; P < 0.001), while mean Tsk (P < 0.001) and HR (P < 0.001) differed between all conditions (HOT>WARM>COOL). Task speed and accuracy during welding and plank-walking were similar between conditions (all P > 0.05). However, postural sway velocity during welding increased (by 2.08 ± 2.5 mm.s-1; P < 0.05) from baseline to post-trial in HOT but not in WARM or COOL (both P > 0.05).

Conclusions: Although task performance was maintained across environments, postural balance during an attention-demanding task (welding) was impaired following physical work in Singapore's projected environmental conditions, which could increase the risk of potentially fatal accidents and injuries (e.g., falling from height). Effective workplace interventions are needed to protect workers' health, safety and productivity against future warming.