Bangladesh frequently experiences extreme heat and humidity, which threatens the health, wellbeing, and productivity of ready-made garment workers. Scalable, sustainable, and low-cost cooling strategies are urgently needed to protect this workforce in low-income and middle-income countries. Therefore, we examined the effects of building-level and personal-level cooling alternatives to air conditioning on worker heat strain in a simulated Bangladesh ready-made garment factory.

In a randomised cross over trial (ACTRN12622000457741), healthy participants (aged 18–40 years) recruited from a convenience sample of volunteers from diverse ethnic backgrounds completed six 3-h gender-specific ready-made garment work simulations (males ironed and females sewed) in a climate chamber at the University of Sydney: (1) current factory (control [CON]=40°C, 38% relative humidity); (2) CON with fan (FAN); (3) FAN with drinking water (FAN+HYD); (4) modified rooftop (ROOF=37·5°C, 38% relative humidity); (5) ROOF with fan (ROOF+FAN); and (6) air conditioning (AC=24°C, 40% relative humidity). Primary outcomes were end-trial core temperature, heart rate, and sweat loss fluid deficit. Linear mixed models with fixed effects of intervention and sex and random effects of participant were used for analysis. Pre-planned contrasts compared each intervention to CON, with Dunnett’s correction for multiple testing.

Between March 16, 2022, and Nov 25, 2023, 42 participants (20 identifying as females, 22 as males) completed 247 trials. Compared to CON, male core temperature decreased with FAN+HYD (–0·27°C [99% CI –0·44 to –0·09]), ROOF (–0·35°C [–0·53 to –0·17]), ROOF+FAN (–0·28°C [–0·45 to –0·10]), and AC (–0·71°C [–0·89 to –0·53]), but in females, core temperature decreased only with AC (–0·42°C [–0·60 to –0·24]). Male heart rate was lower with FAN (–6 beats per minute [–12 to 0]), FAN+HYD (–13 beats per minute [–19 to –7]), ROOF (–8 beats per minute [–14 to –2]), ROOF+FAN (–11 beats per minute [–17 to –5]), and AC (–34 beats per minute [–41 to –28]), and female heart rate was lower with FAN+HYD (–7 beats per minute [–13 to 0]), ROOF (–8 beats per minute [–15 to –2]), ROOF+FAN (–10 beats per minute [–16 to –4]), and AC (–25 beats per minute [–31 to –18]). Male sweat loss fluid deficit was reduced with FAN+HYD (–704 g [–817 to –591]), ROOF (–205 g [–317 to –93]), and AC (–853 g [–966 to –741]), and in females with FAN+HYD (–439 g [–554 to –324]), ROOF (–131g [–246 to –16]), and AC (–513g [–628 to –398]).

Sustainable cooling interventions can reduce physiological heat strain under peak heat stress conditions in a typical non-airconditioned Bangladeshi ready-made garment factory. Cooling benefits were greater in males, highlighting potential gender-based workplace heat stress inequalities.