The hidden nights behind Dhaka's $6bn heat loss

Dhaka is already estimated to lose around $6 billion in labour productivity every year because of extreme heat. New research suggests the economic toll does not end when workers leave their jobs.

Increasingly hot nights, overcrowded housing and frequent power outages are preventing thousands of low-income workers from recovering after physically demanding shifts, leaving them exhausted before the next workday even begins.

Researchers describe this as a growing "recovery deficit"...a largely overlooked consequence of climate change that is undermining workers' health, reducing productivity and increasing vulnerability to heat-related illnesses.

The findings come from Hot Cities Make Hard Work Harder, a study by People's Courage International and ISET International covering informal workers in Dhaka, Delhi, Jakarta, Kathmandu and Quezon City. 

In Bangladesh, the research was conducted in partnership with the Ovibashi Karmi Unnayan Program (OKUP).

The report arrives as Dhaka continues to warm faster than much of the country. According to the World Bank, the capital's maximum temperature increased by 1.4°C between 1980 and 2023, compared with a national average increase of 1.1°C, making Dhaka one of Bangladesh's fastest-warming urban areas. 

Researchers attribute much of the increase to rapid urbanisation, shrinking green spaces and the urban heat island effect, where concrete, asphalt and dense construction trap heat long after sunset.

For many migrant workers, escaping the heat is nearly impossible.

New arrivals to the capital often live in single-room dwellings shared by five to eight people, with poor ventilation, unreliable water and sanitation services, and thin metal roofs that absorb heat throughout the day. 

In many industrial neighbourhoods, electricity outages remain common, leaving residents without fans during the hottest hours of the night.

As indoor temperatures remain high well after dark, many families spend hours outside before returning home, only to find their rooms still too hot for restful sleep.

"After a long day of work, I come home hoping to rest, only to find there's no electricity due to load-shedding. The intense heat becomes unbearable," a construction worker in Dhaka told the researchers.

Worker representatives say the findings reflect conditions they regularly observe.

"I agree with the findings of the report," said Kalpona Akter, president of the Bangladesh Garment and Industrial Workers Federation (BGIWF).

"Besides the heat, there is often no electricity, and the rooms where workers live are so congested that there is hardly any ventilation. As a result, workers cannot fully recover from the fatigue and exhaustion they experience before returning to work the next day. Over time, this inevitably affects their ability to work and reduces productivity."

Researchers say inadequate overnight recovery has direct consequences for workplace performance. Workers who cannot cool down or sleep properly begin the next day already fatigued, reducing physical capacity, concentration and decision-making while increasing the risk of heat stress and occupational injuries.

The findings build on a 2022 study by the Adrienne Arsht-Rockefeller Foundation Resilience Center, which estimated that extreme heat already costs Dhaka approximately $6 billion annually in lost labour productivity—equivalent to around 8 percent of the city's annual labour output.

Among the 12 global cities analysed—including New Delhi, London, Los Angeles, Sydney, Athens, Buenos Aires, Miami and Santiago—Dhaka recorded the largest productivity losses, reflecting its labour-intensive economy, high levels of outdoor and factory work, and limited access to cooling.

The latest research suggests those losses are likely being underestimated because they largely account for heat exposure during working hours. Night-time heat, researchers argue, continues to impair workers' ability to recover, extending the effects of extreme temperatures well beyond the end of the workday.

The financial burden is also reaching households.

Workers interviewed for the study reported rising spending on electricity, drinking water, transport and medicines while incomes remained largely unchanged. 

Many also said employers provide limited protection from extreme heat, with inadequate access to drinking water, cooling facilities or sufficient rest breaks.

Conditions are particularly challenging in smaller subcontracting garment factories, where overcrowded production floors and poor ventilation expose workers to prolonged heat.

The issue carries broader economic implications for Bangladesh, where ready-made garments account for the country's largest export earnings and millions of workers are employed in labour-intensive manufacturing. 

The International Labour Organization has previously warned that rising temperatures could substantially reduce working hours and labour productivity across South Asia as climate change intensifies.

The researchers argue that reducing heat-related productivity losses will require measures beyond workplace safety. 

Alongside improving working conditions, they say cities will need cooler and better-ventilated housing, expanded urban green spaces, more shade and a more reliable electricity supply to help workers recover between shifts.