The research by Cornell University titled ‘Six seasons, four summers: Inside fashion’s high heat problem and how to solve it,’ examined heat exposure in eight garment factories in Dhaka over a year. It found that heat stress was associated with an average 4.1% loss in working-time productivity across the sites assessed.
Researchers combined temperature and humidity readings from factories and 37 workers’ homes with worker surveys and engineering assessments.
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Cornell conducted the work with BRAC University, YGEN Engineering and the Bangladesh Centre for Worker Solidarity.
Dhaka experienced a seven-month heat-stress season in 2025, which the researchers described as “the new norm”. Heat levels inside factories consistently exceeded those outdoors, with ironing and finishing areas recording the greatest exposure.
Workers in those sections spent a substantial proportion of their time during the hottest months in caution, high or severe heat-stress zones. Survey results showed that workers often continued working in high heat despite dangerous conditions.
Engineering assessments identified roof insulation, improved ventilation and mechanical cooling as measures that could lower exposure. The report found that these interventions could generate financial returns through productivity improvements as well as reducing risks to workers’ health and safety.
Under a “headwinds” scenario, the average payback period across the factories was 2.9 years. In the worst-case scenario examined, it was slightly more than four years.
The researchers said the business case remained positive after allowing for higher capital and energy costs and lower productivity gains.
A wider programme to address high heat stress across Bangladesh’s apparel export industry would require an estimated $239m in capital expenditure, according to the report. Spread over three years, that would equal 0.2% of the sector’s 2025 apparel export revenue.
The study also examined conditions away from the workplace. Hotter nights were found to be limiting workers’ recovery after shifts, while increased spending on electricity, medicine and other household needs added to financial pressure.
Workers reported borrowing money, pawning belongings or reducing other spending to pay for fans, electricity and healthcare during the hottest months.
Cornell University’s Global Labor Institute executive director Jason Judd said: “The problem is urgent and we already know what can be done to reduce heat stress. There are practical solutions available to manufacturers. Addressing heat stress makes sense from both business and worker health and safety perspectives. The challenge now is deciding how to share the costs fairly and scaling these solutions across the industry. This means acting together – employers, buyers, workers, government – including through mandatory programmes such as the International Accord, which provide a framework for putting solutions into practice and spell out how responsibility is shared.”
The findings follow Cornell’s 2023 Higher Ground research with Schroders, which estimated that extreme heat and flooding could put $65bn in apparel exports at risk across Bangladesh, Cambodia, Pakistan and Vietnam by 2030.
For Bangladesh, the earlier analysis put $27bn in exports and 250,000 potential jobs at risk.
The research argues that heat adaptation will require coordination between manufacturers, international buyers, workers, government and institutions, rather than being treated solely as a factory-level expense.
In addition, the report said heat-stress measures should be tailored to the conditions and operational needs of individual factories, rather than applying a single approach across the sector.
YGEN Engineering Dhaka managing director Tareq Ahmed Robin said: “There is no one-size-fits-all solution to heat stress. Every factory is different, so measures need to reflect the factory’s design and production processes. The important thing is to start now, with practical steps – insulation, improved airflow, active cooling for the hottest areas — and to build on these measures as heat stress rates go higher.”
