Beat the Heat: How to Stay Safe as Temperatures Rise this Summer

BU Experts
7 min readJul 1, 2021


Environmental health expert discusses the links between heat and health and provides tips on how to stay cool.

By Katherine Gianni and Molly Gluck

Photo by Pawel Janiak on Unsplash.

Summer is upon us and things are heating up, literally. The first major heatwave of the season scorched the western United States last week, with temperatures climbing to 114 degrees Fahrenheit in Las Vegas, Nevada, to a record-breaking 118 degrees in Phoenix, Arizona. And the scorching conditions didn’t stop there. The Pacific Northwest has shattered previously recorded temperature highs since Saturday, June 26, with many regions trapped under what experts are calling a blistering “heat dome.Here in Boston, the city tied its record highs (that have stood since 1933) on June 28 and 29, causing a heat emergency to go into effect for the city. Unfortunately, these are not isolated events: the first comprehensive worldwide assessment of heatwaves down to regional levels uncovered that in nearly every part of the world, heatwaves have been increasing in frequency and duration since the 1950s. With July and August still ahead, meteorologists and climate scientists alike are wondering what lies in store for those anxious to beat the heat and protect the health and safety of themselves and loved ones. For recommendations, we turned to Dr. Gregory Wellenius, a Boston University professor of environmental health.

Dr. Wellenius is an environmental epidemiologist whose research is focused on assessing the human health impacts of a rapidly changing climate. His team aims to provide the actionable scientific evidence needed to ensure that our communities are as resilient, sustainable, and healthy as possible — emphasizing the benefits to human health of climate change mitigation and adaptation efforts. He discussed the physical and mental health impacts stemming from extreme heat exposure, ensuring equitable access to community ‘cooling centers,’ and how to stay safe when temperatures reach dangerous highs.

What research methods do you use to evaluate the impacts of heat on health?

My team links detailed data on local weather to very large clinical datasets in order to study the impacts of heat and other climate hazards on people’s health and well-being. We then use sophisticated statistical methods to quantify the impacts of extreme heat on a range of clinical outcomes in communities around the country.

What happens to the body as a result of exposure to extreme heat?

Hot days can lead people to suffer from dehydration, heat exhaustion, and in extreme cases, heat stroke. But hot days are also associated with higher risk of a number of other conditions that are not typically thought to be ‘heat-related,’ such as renal problems, skin infections, and preterm birth among pregnant women. In fact, heat stroke, heat exhaustion, and dehydration account for a relatively small fraction of the total burden of disease associated with days of extreme heat. And interestingly, it’s not just extreme heat that poses a risk. Even moderately hot days can place vulnerable individuals at higher risk.

What happens to the brain as a result of exposure to extreme heat in terms of mental health and cognition?

A growing body of evidence suggests that days of high temperatures may negatively affect our mental health. For example, a recent study in New York found that hot days were associated with higher risk of emergency room visits for substance abuse, mood and anxiety disorders, schizophrenia, and dementia. Other studies show that hot weather is linked to lower performance on standardized tests, higher risk of judgement errors, and higher risks of occupational injuries. So although there is a lot more work to do to get the full picture, it is becoming clear that heat has important effects on cognition, mood, and other aspects of our mental health and well-being.

Are there demographic factors that affect how vulnerable a population is to heat?

Very hot days put everyone at risk, but there is no question that some groups and some communities are at greater risk than others. Outdoor workers — such as agricultural workers, construction workers, and landscapers — are at particularly high risk of heat-related illness. The elderly, pregnant women, those with certain pre-existing diseases, and those without access to air conditioned spaces are also thought to be at higher risk. In some communities, the lack of trees and parks makes those neighborhoods even warmer than the surrounding areas, contributing to the urban heat island. People that live in urban heat islands are also thought to be at higher risk.

Photo by Josh Olalde on Unsplash.

What are the differences between weather and climate?

Weather refers to the local conditions outside today, this week, or this month — while climate describes the typical weather over a period of 30 years or longer. Continued climate change makes extreme weather events such as days of high heat, hurricanes, wildfires, or droughts more likely.

Your recent research found that how dangerous a hot day is may depend on where you live. Can you please explain why this is?

Over time people and communities partially adapt to their local climate. For example, homes in Phoenix or Houston (cities that tend to have many hot days each summer) are more likely to have air conditioning as compared to homes in cities such as Portland, Maine or Seattle where summers are historically less hot. The typical climate in an area affects many aspects of how we live, move, work, and play. Characteristics of the population can also affect vulnerability to heat. So for example, communities with many older individuals or with more people working outdoors may face a higher risk than neighboring communities with different demographics.

Is access to cool spaces equitable during times of extreme heat?

No. Many people have access to cool spaces during extreme heat either at work or at home. However, not everyone works in an air conditioned office or store and not everyone can afford the electricity needed to run a home air conditioner. In fact, those people that are most vulnerable to heat are often the ones with the least access to cool spaces. Some cities open or advertise designated ‘cooling centers’ open to the public during extreme heat events, but these may not be accessible to those without transportation or those that need to work during the day, and still leaves many vulnerable people at risk.

Photo by Toshi Kuji on Unsplash.

What steps can people take to protect their health when temperatures are extremely high?

The most important thing for everyone to do is to be aware that the health risks of extreme heat are real and important. Individuals should stay out of the sun as much as possible, drink a lot of water, and find places to cool off when needed. It’s also important that we all check in on our neighbors and loved ones to see if they need help or care, as not everyone recognizes the risks of extreme heat or has the means to seek cool spaces or medical attention when needed.

What principles should guide heat action plans? How should they be created and implemented on a local and national scale? What will successful heat action plans achieve?

Every community is different in terms of the risks, vulnerabilities, and resources. That means that heat action plans need to be developed by local agencies in partnership with the local communities they serve, but building on best practices and shared knowledge from other regions. There is no one-size-fits-all heat action plan.

What are the major challenges, if any, for researchers studying climate change and health linkages?

The key challenge I see is how to make research results actionable. As a community, we need to move beyond merely describing problems and health threats to creating, testing, and refining solutions that protect public health in the real world and with a particular focus on doing so in an equitable manner. We need to provide the evidence needed to empower any community in the country or in the world to protect themselves from the increasing threats posed by continued climate change. Finding local solutions to global problems is a big challenge, but doing so has never been more important.

Photo by Markus Spiske on Unsplash.

Are there challenges in communicating climate and temperature-related threats to health? How would you respond to claims that extreme weather patterns are normal?

Climate change isn’t about the future or danger to people in some far off place. The threat from climate change to our health is real, with material impacts on all of our communities right now. Although there are many aspects of climate change that can be contentious, no one wants to see their friends and loved ones suffer from death, disease, or distress. We need to share with people how climate change threatens our health and well-being today and the enormous cost of continued political inaction. Climate change is already impacting nearly every aspect of how we live, work, and play. Taking action today can help us avoid even worse outcomes in the future.

For additional commentary by Boston University experts, follow us on Twitter at @BUexperts. Follow Professor Wellenius at @gwellenius. For research news and updates from BU’s School of Public Health, follow @BUSPH and the Department of Environmental Health at @busphEH.



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