Extreme Heat and Work

How rising temperatures reduce productivity and threaten outdoor workers, and what economists estimate about the costs of extreme heat.

Heatwaves may not destroy buildings like earthquakes, but they are among the deadliest hazards. Extreme heat also quietly reduces how much people can work and learn.

Heat and productivity

When temperatures are very high, the human body struggles to cool itself. Workers slow down, take more breaks and make more mistakes. Outdoor workers in farming and construction are most affected, but factory and office workers without cooling suffer too.

The International Labour Organization projected in 2019 that heat stress could reduce total working hours worldwide by about 2.2 percent by 2030, equivalent to 80 million full-time jobs, with South Asia and West Africa among the hardest-hit regions.

Evidence from India

Research on Indian factories by E. Somanathan and co-authors found that worker output fell on hotter days. They also found that factories that installed cooling saw smaller drops in productivity. Studies in several countries have found that students score lower on tests taken on hotter days, and that more hot school days are linked to lower learning over time.

A construction worker's day

On a normal day, a construction worker lays a certain number of bricks. On a day above 40 degrees Celsius, they must work more slowly and rest more often to avoid heat exhaustion, laying far fewer bricks. If the heat lasts for weeks, the lost output adds up, and workers paid by the day or task lose income.

Heat action plans

Some cities have developed heat action plans to reduce harm. Ahmedabad in India launched one of South Asia’s first in 2013, after a deadly heatwave in 2010. Its measures include early warnings, public awareness, cool drinking water stations, adjusted working hours for outdoor workers and hospital preparation. Other Indian cities and states have since adopted similar plans.

Adaptation and inequality

Air conditioning reduces heat’s effects but costs money and electricity, so richer households and firms adapt more easily. This means heat tends to widen inequality. Cheaper adaptations include cool roofs painted with reflective paint, shade trees, and shifting outdoor work to cooler hours.

Thinking heat only matters during rare heatwaves

Economists find that productivity losses begin well before the most extreme temperatures, and add up across many hot days each year. As average temperatures rise, these everyday losses may be as important as dramatic heatwaves.

Key takeaways

Extreme heat reduces worker productivity and learning, especially outdoors.
The ILO projected heat could cut global working hours by 2.2 percent by 2030.
Ahmedabad's 2013 heat action plan became a model for other cities.
Adaptation like cooling favours richer households, so heat can widen inequality.