Soaring city heat endangers working people

A new international study has warned that rising temperatures and worsening climate conditions are placing Dhaka’s rickshaw pullers at increasing risk of heat-related illness, with occupational survivability expected to deteriorate sharply over the coming decades.

The study, titled Forecasting Occupational Survivability of Rickshaw Pullers in a Changing Climate with Wearable Data, was conducted by researchers from the University of California San Diego, Bangladesh University of Engineering and Technology (BUET), and Cornell University.

Researchers collected real-time physiological and weather data from 100 rickshaw pullers in Dhaka using wearable sensing devices, while 12 additional pullers were interviewed about their experiences and perceptions regarding climate change.

The study found that 32 per cent of rickshaw pullers are already exposed to a “high risk of heat-related illness” or “extreme conditions” during regular working hours, based on Wet Bulb Globe Temperature (WBGT) exceeding 31.1°C. Researchers warned that this figure could rise to 37 ±17 per cent by 2026-2030 and to 53 ±15 per cent by the end of the century under mid-range warming projections.

The researchers observed that rickshaw pullers currently remain exposed to dangerous heat for an average of 10 minutes per trip, equivalent to 58 per cent of trip duration. By 2091-2100, exposure duration may rise to 14.2 ±2 minutes, or nearly 79 per cent of trip time.

The study also highlighted alarming physiological impacts. Exposure based on skin temperature above 35°C – considered dangerous because prolonged exposure may elevate core body temperature – currently affects 20 per cent of participants. This proportion is projected to increase to 42 ±16 per cent by the end of the century.

Researchers used wearable devices to monitor skin temperature, cardiac strain, sweat gland activity and movement during rickshaw trips lasting around 15-25 minutes. The participants, all male, had an average age of 48 years and typically worked 10 hours daily earning around six US dollars per day.

The findings revealed strong correlations between extreme weather and physiological stress indicators, including skin temperature, cardiac cost and sweat response.

“Those rickshaw pullers who drive with more intensive activity have their skin temperature tend to increase,” the study noted, adding that higher temperatures and humidity significantly intensified physical strain.

The research further found that older rickshaw pullers required greater cardiac effort compared to younger workers, while many participants reported chronic pain in their hands, legs, knees and heads due to the physically demanding nature of their work.

Using projections from 18 CMIP6 global climate models under different greenhouse gas emission scenarios, researchers forecast a significant rise in Bangladesh’s surface temperature by 2100, even under relatively low-emission pathways.

The study identified skin temperature as the most reliable biomarker for forecasting occupational heat survivability because of its direct relationship with core body temperature regulation.

Interviews with rickshaw pullers also revealed growing concern over worsening urban heat conditions.
“While heat persists year around, what comes during the monsoon season, after Ashar, is unlike anything I’ve experienced before,” said a 52-year-old rickshaw puller with 25 years of experience.

Another participant said, “Due to the increase in temperature, I feel weaker, and it affects my health. If it gets too hot, my body lacks energy, which makes me feel tired.”

Researchers said the findings underline the urgent need for climate adaptation measures and occupational protection strategies for vulnerable outdoor workers in Bangladesh and other climate-sensitive urban regions.