Older adults in Bangladesh face over 2,500 hours of extreme heat a year: Study 

Older adults in Bangladesh now face more than 2,500 hours of extreme heat each year, severely limiting safe outdoor activity, according to a new international study published today (10 March). 

The research, published in the journal Environmental Research: Health, warns that rising temperatures and humidity are increasingly restricting daily life for millions and pushing parts of South Asia towards conditions scientists describe as "unlivable".

In the mid-20th century, older adults in Bangladesh experienced about 2,180 hours of such heat annually, indicating a sharp rise in life-limiting heat exposure over recent decades.

In practical terms, elderly people in Bangladesh now face nearly one-third of the year when activities beyond slow walking or light household tasks may pose risks of heat-related illness.

Researchers say Bangladesh is particularly vulnerable due to its high humidity, dense population and warming climate. 

The study found older adults in Bangladesh, Cambodia and Thailand now experience between 2,000 and 2,800 hours of severe heat annually — hundreds more than in the 1950s.

Heat risks rising worldwide

The study, led by researchers from The Nature Conservancy and several international institutions, analysed more than 70 years of climate data from 1950 to 2024 using a physiological model to assess how the human body responds to heat.

The findings show that about 35% of the global population now lives in regions where extreme heat severely limits safe physical activity during the hottest periods of the year, even for younger adults.

Globally, younger adults now face around 50 hours of severe heat-related activity restrictions each year, double the level in the 1950s. For people aged 65 and above, the figure has risen to about 900 hours annually.

'Unlivable' conditions emerging

Researchers also identified areas where extreme combinations of heat and humidity could create "unlivable" conditions, meaning even resting in shaded and ventilated environments may pose serious health risks. 

About 24.5% of the global population now lives in regions that experience such conditions for older adults during the hottest hours of the year, particularly across the Indo-Gangetic Plain, including large parts of Bangladesh and eastern India.

Although some wealthy Gulf countries record higher extreme heat hours, scientists say the human impact is greater in South Asia due to large populations and limited cooling infrastructure. 

India, Bangladesh and Pakistan rank among the most exposed countries when measured in "people-hours" of heat exposure.

A rapidly warming planet

The study comes as global temperatures have already risen by nearly 1.5°C above pre-industrial levels, with 2024 recorded as the hottest year on record. 

During that year, more than 43% of younger adults and nearly 80% of older adults worldwide experienced periods when heat and humidity severely limited daily activity.

Scientists warn that without rapid cuts in fossil fuel use, heat-related limits on everyday life will continue to expand. 

Researchers say measures such as cooling centres, early-warning systems and improved urban planning can help reduce risks.