Millions of people are impacted by heat-related events every year—and it’s only getting worse.
Many parts of Europe are currently experiencing an intense heatwave with some places reaching up to 97°F (36.1°C), the hottest temperature ever recorded in June. Despite the unsafe conditions, some teachers in France are finding creative ways to navigate dangerously overheated schools—and they are also calling for support. In a joint statement, several teaching unions condemned the government for its “blatant lack of preparation” as some classrooms reach temperatures of up to 104°F (40°C).
Over the past two years, we have covered the impacts of extreme heat on children and athletes and pregnant individuals. This year, we will focus on another vulnerable group: indoor and outdoor workers.
The impact of heat on indoor workers
Individuals who work in indoor environments such as commercial kitchens, manufacturing facilities, and warehouses frequently face significant heat exposure. This can be due to inadequate climate control, enclosed spaces, and heat-generating appliances like ovens and furnaces.
A report from the 2025 Shift Project analyzed heat exposures among more than 3,500 service workers in retail and food services. The report revealed that nearly half of the surveyed workers are exposed to workplace temperatures that meet or exceed the 80°F threshold used by the Occupational Safety and Health Administration (OSHA) for defining dangerous heat exposure.
This climate issue also affects those who work remotely or spend the majority of their time indoors with inadequate cooling systems. Since the pandemic, remote work has increased. In Europe, an estimated 8.9% of the population works at least part-time from home offices, but the number is much higher in some countries (e.g., 19.6% in Finland, and 20.6% in Ireland). Only 20% of homes in the region have air conditioning.
Historically, European countries have not needed indoor cooling due to relatively mild summer temperatures. Some buildings in the southern European countries were built for the heat, with thick walls, small windows, and designed to maximize air flow. However, other parts of Europe have not been designed with heat in mind. According to Brian Motherway, head of the Office of Energy Efficiency and Inclusive Transitions at the International Energy Agency in Europe, “We haven’t been in the habit … of thinking about how we stay cool in the summer. It really is a relatively recent phenomenon.”
The recent heatwaves in Europe have been prolonged, lasting for days and weeks. This makes it increasingly challenging for individuals to cool down and stay safe, and has even resulted in a growing number of heat-related deaths.
Addressing the dangers of heat for outdoor workers
People who work outdoors, particularly those in agriculture, fishing, and construction, face heightened heat-related illnesses and injuries—particularly when there is limited access to cooling, water, or shade.
Specifically, jobs that require intense physical labor, layers of protective clothing, and those in urban environments can make conditions more dangerous. Outdoor workers in cities may suffer from increased temperatures due to the urban heat island effect, which can increase temperatures by 18-27°F (10-15°C) during the day, and 9-18°F (5-10°C) at night when compared to rural areas.
A week ago, New York City Mayor Zohran Mamdani signed an Executive Order directing a “whole-of-government response” to protect outdoor workers from extreme heat—the first initiative of its kind in New York City history.
This order expands the NYC Emergency Management (NYCEM) “Beat the Heat” program by developing and distributing multilingual heat safety guidance for outdoor workers as soon as next year. The order will require every mayoral agency to develop and implement heat illness prevention plans for NYC employees and contractors. The Department of Health and Mental Hygiene (DOHMH) will also research and evaluate whether heat illness should be a reportable health condition, and the Department of Buildings (DOB) will also review and strengthen construction site heat safety requirements with recommendations by March 2027.
Additionally, for the first time in NYC history, more than 2,200 LinkNYC kiosks will display real-time walking directions to the nearest Cooling Center within a 10-minute radius, automatically updating data via the City’s Cool Options Finder. Guidance for indoor workers will be issued early next year.
“No one should have to choose between their paycheck and their health. . . The workers building our skyline, delivering our packages, selling food on our street corners and keeping this city running deserve to come home safe at the end of every shift. In the past, workers have borne the burden of extreme heat while the government looked the other way. We’re changing that because every worker’s life is worth protecting. As summer heats up, we’re taking a whole-of-government approach to keeping New Yorkers prepared, safe and cool.”
In addition to the health risks, extreme heat has significant economic consequences. Without proper regulations and protection, work disruptions due to heat could cost the U.S. an estimated $55.4 billion in annual losses, according to a recent study by the Union of Concerned Scientists. The heat-related disruptions could heavily impact food production, construction, and supply chains.
Staying cool while working outdoors
The following tips from the CDC provide guidance on how to stay safe while you work outside:
- Prevent heat illness with acclimatization
- Drink plenty of water, even when you are not feeling thirsty
- Avoid alcohol or drinks with high amounts of sugar
- Wear and reapply sunscreen
- Limit tasks to earlier or later in the day to avoid peak heat
- Wear a brimmed hat and loose, lightweight, light-colored clothing
- Spend break times in air-conditioned spaces
Staying informed about upcoming heat events is also critical—and not just for workers. In 2025, California became the first state in the nation to launch a heat-ranking system, CalHeatScore. This tool was developed to keep Californians safe during extreme heat by translating complex weather and health data into clear guidance. Last month, Governor Newsom announced that they will be expanding access to CalHeatScore, providing live data and resources to residents.
“California is turning cutting-edge data and technology into real-world protection, giving people the power to see extreme heat coming and act early. As temperatures rise, this innovation helps safeguard lives, strengthen resilience, and ensure no one is left behind.”
If you or someone you know is experiencing symptoms of heat-related illness, seek medical assistance and call the doctor or 911 right away, and cool the person quickly.
Explore the following resources for additional information and tips:
- Collaborative for Health and Environment (2019). Climate Change and Heat: Health effects, adaptation strategies, and the benefits of mitigation.
- Collaborative for Health and Environment (2023). Playing on Plastic: Artificial Turf Hazards and Safe Alternatives.
- Collaborative for Health and Environment (2024). Summer Heat (Climate Change Version).
- Collaborative for Health and Environment (2025). Climate Change, Heat & Pregnancy: Health risks rise with temperatures
- Sustainable Energy for All (2026). Chilling Prospects Data Story: Addressing the Dangers of Heat for Outdoor Workers
- Yale Program on Climate Change Communication (2025). Heat, work, and worry: How is outdoor employment linked to concern about extreme heat?