Extreme heat is increasingly disrupting the health, livelihoods and daily lives of people living in informal settlements across Africa, with many forced to miss work and struggling to sleep as temperatures rise, according to a new report.
Research by the International Institute for Environment and Development (IIED) found that about a quarter of residents surveyed in African slums had to take time off work due to intense heat, while 40 percent reported difficulty sleeping because of high temperatures.
The study, carried out with Slum Dwellers International, surveyed more than 1,000 residents in informal settlements in Mathare in Kenya, Kombo in Tanzania and Kariba in Zimbabwe.
Researchers said the findings highlight how rising urban temperatures are increasingly affecting some of the most vulnerable populations in rapidly growing African cities.
“Heatwaves and other extreme weather can derail productivity, disrupt children’s schooling and cause health problems,” said Anna Walnycki, a principal researcher at IIED.
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Across the three communities surveyed, about 70% of respondents said they had experienced health problems linked to extreme heat, including dehydration, fatigue and heat stress.
Indoor temperatures were found to reach as high as 40 degrees Celsius (104°F), sometimes as much as nine degrees higher than outdoor temperatures.
Researchers said conditions in informal settlements often intensify the impact of heat. Densely packed housing, limited ventilation and building materials that trap heat can make homes significantly hotter than surrounding areas.
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Unplanned settlements also tend to have fewer trees and little green space, factors that would otherwise help cool urban environments.
Poorer residents are particularly exposed because many rely on informal work and lack access to employment protections such as paid sick leave, meaning lost workdays directly affect their income.
The financial burden of coping with rising temperatures is also growing. More than one-third of households surveyed said they were spending additional money during periods of extreme heat, equivalent to about one-sixth of their monthly income in some cases.
Residents reported using the money to buy water, cooling devices or materials to improve ventilation in their homes.
By contrast, wealthier households in formal urban neighbourhoods are more able to adapt by installing air conditioning, upgrading housing materials or living in areas with more vegetation and lower temperatures.
Safety concerns have also emerged as residents try to cool their homes.
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Some participants in the study said they leave windows open at night to improve airflow, exposing themselves to potential crime.
“Focus group participants said sometimes their only option is to leave windows open at night which leaves them vulnerable to crime,” said Mussa Raido, a researcher at the Centre for Community Initiatives in Tanzania who helped collect data for the survey.
The report warned that the problem is likely to worsen as climate change drives higher temperatures in cities across the Global South.
More than one billion people worldwide currently live in informal settlements, a number expected to rise sharply by 2050 as urban populations continue to expand.
Researchers said more data is needed on how extreme heat affects residents in low-income urban communities, where conditions are often poorly monitored.
The report also called for measures such as early heat warning systems, better ventilation in housing and urban greening programmes to reduce heat exposure.
Planting trees in densely populated neighbourhoods could provide shade and help lower temperatures, while also improving food security in some communities.
“Education for slum dwellers is key, particularly around planting and protecting trees that can give them the shade they desperately need,” Raido said.
The findings underline growing concerns that climate change is amplifying existing inequalities, with poorer urban residents facing some of the most severe impacts of rising global temperatures.
