Talking with U of M

Talking heatwaves and health impacts with U of M

Man in sun
AntonioGuillem from Getty Images

If you find yourself thinking, “it never used to be this hot” — you are correct. This May, the National Oceanic Atmospheric Administration (NOAA) released its once a decade report called U.S. Climate Normals. 

This report — which analyzes thirty years of data — illustrates that from 1991-2020, the U.S. has averaged warmer temperatures and more extreme heat compared to previous decades. In addition, the last four decades have also reported the wettest atmosphere on record for the U.S. The combination of extreme heat and moist or humid air poses a serious threat to human health because humidity limits the body’s ability to regulate its core temperature.

As Minnesotans experience extended heat this summer, Teddie Potter with the University of Minnesota School of Nursing provides tips about how people can survive and protect their health during times of extreme heat.

Q: How does extreme heat impact the body during short and long periods of time?
: Our bodies are exquisitely designed to adapt to heat. Through a series of complex adjustments — such as fluid, salt regulation, and sweating — our hypothalamus regulates our internal core temperature to remain within one to two degrees of 98.6 Fahrenheit. 

The health impacts of extreme heat are the result of many factors, including the length of exposure, the level of humidity, and the temperature during the nighttime. For most people it is not dangerous to be outside for short periods of time on extremely hot days. The real dangers come with prolonged exposure:

  • to direct sun;
  • elevated humidity that decreases the body’s ability to regulate temperature; through sweating and evaporation;
  • poor fluid intake;
  • extreme exertion that generates additional body heat; and,
  • nights when the temperatures fail to fall below 80 degrees Fahrenheit. 

Again, we can tolerate short periods of extreme heat, but days and days of unrelenting heat take their toll, especially for people who lack access to a cooler indoor environment.

It is important to know that once heat exhaustion sets in, people can become confused and may not take the necessary steps to remove the heat threat. It is up to all of us to be aware of the signs of heat exhaustion so we can assist neighbors in need. 

Q: Can people still exercise or be out for periods of time in the heat? 
: A variety of internal and external factors can limit our body’s capacity to adapt to extreme heat. Internal factors include age, chronic illness, alcohol use, and some prescription medications. Infants and young children lack effective thermoregulation and are at particular risk for sudden heat stress or heat stroke. People over the age of 65 perspire less and are therefore unable to cool their bodies through evaporation. Those with underlying cardiovascular conditions are at added risk of severe heat-related health impacts because poor circulation limits the body’s ability to release heat through the skin. In addition, alcohol, antidepressants and drugs that treat Parkinson’s disease also impact thermoregulation.

External factors that challenge our ability to adapt to extreme heat include lack of housing or housing without air conditioning. Especially if people are living in urban heat islands, have less accessible shaded greenspace and limited access to drinking water. When days of extreme heat occur, our body’s natural heat regulating mechanisms need assistance in the form of decreased environmental temperature and increased water consumption. If these measures are not in place, there is an added risk of heat strokes and even death.

Q: Are there measures people should take to help deter heat exhaustion and heat stroke?
: We can all feel hot when temperatures are extreme but heat exhaustion and heat stroke are particularly dangerous. Heat exhaustion is an early warning that our body is losing its ability to shed enough heat. Common symptoms include rapid pulse, heavy sweating, cool moist skin, nausea, headaches, dizziness, fatigue, and occasionally muscle cramps. If someone experiences these symptoms, they need to seek shade or a cool indoor setting immediately, decrease any form of exertion and push fluids.

If these early signs are ignored, the person can experience a heat stroke, which is when the core body temperature reaches 104 degrees Fahrenheit or more. Without immediate medical attention, heat stroke can be life-threatening. The best ways to prevent heat exhaustion and heat stroke are protection from the sun, adequate hydration, a natural or fan-generated breeze, and decreased exertion.  

Q: Who is most affected by days of extreme heat and how can they be helped?
: Exercise is always a good way to maintain health, but we need to take several precautions during extreme heat. Exertion and dehydration put people at added risk for heat strokes, so it is highly recommended that people exercise outside during the early morning hours or later in the evening once the daily high temperature has passed. People can also exercise for shorter periods or choose less strenuous exercises on extreme days. 

On days of extreme heat, all of us need to push fluids, but even more fluids if we are more active and sweating more. One important indication to note is the color of our urine; if it is dark yellow, the body does not have the fluids it needs to maintain a safe temperature. 

Exercise is a choice. It is not a sign of weakness to remain indoors or exercise indoors when heat is extreme. For migrant workers and construction workers, however, being outdoors in extreme heat is not a choice. Their livelihoods depend on difficult work in challenging climates. Managers and supervisors need to make sure that there is adequate access to sufficient water and some form of air-conditioning or even shade for breaks.

Q: What are you doing to further our understanding of how extreme heat and other effects of climate change impacts our health?
: It is very important to understand that human health depends on a healthy planet. Planetary health is an emerging field of research, education and practice that recognizes human behavior is disrupting the Earth’s natural systems — resulting in threats to our health and the health and survival of future generations. Climate change, biodiversity loss, the acidification of the oceans, loss of forests, and land, water and air pollution are causing real human health issues today. These issues include worsening cardiovascular and respiratory conditions, food and water insecurity, a rise of infectious diseases, decreased mental health, and trauma and strife related to land that is no longer habitable. 

I am honored to be the first director of Planetary Health for the School of Nursing where my focus is educating students, staff, faculty, and community members about current threats like extreme heat and the steps we need to take to heal humans and the planet.

Nursing Professor Teddie Potter, Ph.D., RN, FAAN, FNAP is a leader in the U of M’s Climate Change and Health curriculum, an intersectional project in addressing how to teach the connection between climate and health in existing courses, and leading nursing efforts nationally to advance planetary health. She is a member in the steering committee of the Planetary Health Alliance at Harvard, a Fellow in the National Academies of Practice, she helped lead Nurses Drawdown, an initiative co-sponsored by Project Drawdown and the Alliance of Nurses for Healthy Environments, and she is Chair of the Environment and Public Health Expert Panel of the American Academy of Nursing.


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