Heat is reaching levels resulting in major consequences for health, ranging from short-term impacts such as dehydration and heatstroke to longer term problems such as kidney failure. And, of course, all these hours of education lost to extreme heat also have long-term social and economic impacts<\/a>.<\/p>\n\n\n\n What are urban heat islands?<\/p> Cities often have higher temperatures than the countryside that surrounds them. This is caused by a combination of factors including fewer trees, which can provide shade and cooling; more concrete and brick buildings, which absorb heat; and energy use; which produces waste heat. This is known as the urban heat island (UHI) effect.<\/p><\/div><\/div>\n\n\n\n Two years ago in Argentina, a school drew much public attention after saying pupils could come to school in swimwear because it was so hot. In China, rows<\/a> have broken out online over whether hot classrooms are character building or a health threat. And in the US, researchers are now monitoring individual classrooms as they try to work out how to deal with overheating buildings.<\/p>\n\n\n\n Yet there are scant guidelines in place anywhere for what constitutes a temperature too hot for learning, nor what to do to mitigate against the heat in schools. Advice and policy need to catch up \u2013 and quickly, say a growing number of experts.<\/p>\n\n\n\n Researchers have shown<\/a> definitively that hot classrooms make it harder to learn. A 2018 study analysing 10 million US students\u2019 test scores concluded that \u201cwithout air conditioning, each 1F [0.56C] increase in school-year temperature reduces the amount learned that year by 1%\u201d.<\/p>\n\n\n\n This is a CATCH story<\/p> This story is part of Dialogue Earth\u2019s work on the Community Adaptations to City Heat (CATCH) project, in partnership with Boston University. The project is funded by Wellcome. All Dialogue Earth content is editorially independent.<\/p><\/div><\/div>\n\n\n\n Other research suggests that hot classrooms negatively impact the ability to work, or learn, more than similarly hot offices<\/a> do. Data suggests that the same temperature change impacts learning in children more than office work in adults, although the reasons for this are not clear. Jisung Park, who led that 2018 study and now works at the University of Pennsylvania, has tried to disentangle the complex reasons underlying poor school performance, and consequently economic strength<\/a>, in some hot countries.<\/p>\n\n\n\n Building on the 2018 work, his team looked at standardised achievement data for 58 countries and 12,000 US school districts. They added in detailed weather and academic calendar information and saw that when school days got hotter, there was a decrease in learning as measured by tests. The learning lost to hot days accumulates, and the consequence is lower earning potential for those individuals.<\/p>\n\n\n\n To those on the ground, this is no surprise.<\/p>\n\n\n\n In Nepal, heatwaves have been growing in strength and length in recent years<\/a>. In a country more well known for the chill of the Himalayas than blistering heat, there are very few guidelines in place for dealing with hot classrooms.<\/p>\n\n\n\n \u201cHeatwaves are becoming a common hazard in Nepal,\u201d says Kriti Bhuju, an influencing and communication specialist for Mercy Corps Nepal, a development and relief organisation.<\/p>\n\n\n\n \u201cDespite their growing frequency and intensity, heatwaves are much less considered in the risk assessments and the disaster management plans,\u201d she notes.<\/p>\n\n\n\n This prompted the organisation to instigate a survey of schools in Madhesh province in the south of the country. They found extreme heat there was resulting in increased absenteeism, and more reports of headaches and fatigue, compromising students\u2019 ability to concentrate during lessons.<\/p>\n\n\n\n \u201cClassrooms were poorly ventilated, overcrowded, and in some cases reached dangerously high temperatures, directly compromising student wellbeing and learning outcomes,\u201d Bhuju says. \u201cYet schools had minimal preparedness or response measures in place.\u201d<\/p>\n\n\n\n Heat hasn\u2019t been considered a looming threat in Nepal, Bhuju says. Disaster management focuses on flooding, earthquakes and landslides, rather than slow-onset hazards like heat, she adds. Bhuju hopes that their survey results can feed into policy, particularly local heat-management plans and heat-resistant infrastructure.<\/p>\n\n\n\n \u201cIntegrating heatwave preparedness into the Comprehensive School Safety Framework would be a crucial step forward,\u201d Bhuju says, referring to Unicef\u2019s global strategy<\/a> to protect students and education from hazards of all kinds.<\/p>\n\n\n\n In the UK, another country not typically thought of as hot, researchers are trying to gather enough information to pre-empt a future scenario in which schoolchildren might miss education because of extreme heat.<\/p>\n\n\n\n At the University of York, Lynda Dunlop is a climate change education and sustainability researcher, and Paul Hudson works in disaster risk reduction. Together they ran a survey in summer 2024 asking staff at around 300 schools across the country about their experience of extreme heat. They found 90% of respondents had experienced heatwaves, with most saying they were negatively impacted and saw negative impacts on their students. The survey, which is yet to be published, also looked at around 85 schools\u2019 policies for managing hot classrooms.<\/p>\n\n\n\n \u201cExtreme heat, for the UK at least, isn\u2019t necessarily a huge problem today for schools, but it\u2019s going to become increasingly problematic as we move into the future,\u201d says Hudson.<\/p>\n\n\n\n Schools aren\u2019t as easy to manage as a workplace, Hudson and Dunlop suggest, because of the differences between children and office staff. A primary-school child will be less likely to have the autonomy or knowledge to move to a cooler area than a teacher or high school student, for example.<\/p>\n\n\n\n In the United States, Patricia Fabian at the Boston University School of Public Health has collated a huge data set from a school district in her local area. Her team used heat and air quality sensors installed in over 3,600 rooms within school buildings. Their results show that within a single school building, the difference between the coolest and hottest classrooms could be more than 14C<\/a> on a hot day.<\/p>\n\n\n\n Collecting this data and having sensors in classrooms can allow real-time remediation, like moving to a cooler part of the building, or turning on a window air-conditioning unit in a particular room even if the rest of the school is not too hot, Fabian says. (Window units can be installed cheaply, but can be less efficient to run than central systems that are designed to cool entire buildings.)<\/p>\n\n\n\n \u201cSchools are very resource constrained, and so if they can sample and know what the indoor \u2026 conditions are, whether it\u2019s temperature, carbon dioxide or anything else, they can pinpoint which classroom might have more problems,\u201d she says.<\/p>\n\n\n\n Such data can also feed into longer term strategies for school administrators: \u201cThey can make decisions about where to concentrate the resources for putting air conditioning or trees, or they can make decisions about heat action plans,\u201d Fabian notes. During heatwaves, it could be that school is actually the coolest place for a child to be.<\/p>\n\n\n\n The average US public school was built nearly half a century ago, according to a 2024 survey<\/a>. These facilities were not built to function in our present-day climate. Regions \u2013 ranging from Nepal to the UK, the US and even further afield \u2013 that historically experienced milder temperatures during the academic year are less likely to have air conditioning or other ways of dealing with heat in schools.<\/p>\n\n\n\n Asked if Nepal has guidelines on how hot classrooms are allowed to get, Bhuju\u2019s answer is short: \u201cNot exactly,\u201d she says, though a government policy<\/a> introduced last year does mandate weather monitoring at \u201call local levels\u201d.<\/p>\n\n\n\n Although some countries and regions have imposed maximum temperatures for indoor work, most have no school-specific national guidelines.<\/p>\n\n\n\n What each study highlights is that even more data is urgently needed if evidence-based policy changes are to be enacted. This includes data on how hot classrooms are getting, what temperature is too hot for students to learn in, when schools are supposed to close, and how best to cool things down.<\/p>\n\n\n\n Remediation to cope with heat can be split into two broad areas: infrastructure changes like providing shading, greening the grounds and air conditioning; and behavioural changes like altering school uniform policies, wearing hats outside, moving lessons to cooler rooms and having more breaks for drinks.<\/p>\n\n\n\n For many schools, air conditioning is the one change that will make it possible for children to continue attending, often via window-based AC units. Across the world, such schemes are increasing as temperatures \u2013 and the health risks they bring \u2013 rise.<\/p>\n\n\n\n In the Maldives, minister of education Ismail Shafeeu has announced that all of the country\u2019s 3,704 classrooms will have air-conditioning units installed by the end of 2025 as part of the Cool School Project. In the US, a June 2020 report<\/a> by the Government Accountability Office estimated that 41% of public school districts need to replace or update heating, ventilation and air conditioning (HVAC) systems in at least half their schools. That\u2019s roughly 36,000 schools across the country. <\/p>\n\n\n\nThe impact of heat in classrooms<\/h2>\n\n\n\n
Nepal: Educators struggle in Himalayan heat<\/h2>\n\n\n\n
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<\/div>UK: Rich countries struggle too<\/h2>\n\n\n\n
US: Mass monitoring to beat the heat<\/h2>\n\n\n\n
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<\/div>Seeking school heat solutions<\/h2>\n\n\n\n
Extreme heat is going to become increasingly problematic as we move into the future<\/blockquote>Paul Hudson, a researcher at the University of York, on future threats to the UK\u2019s schools<\/cite><\/div><\/div>\n\n\n\n