MINNEAPOLIS/ST. PAUL (04/06/2022) — Climate change causes more extreme winter weather, wetter springs and hotter summers in the United States. For Earth Month in April, Emily Onello, MD, and Joseph Bianco, MD, with the University of Minnesota Medical School talk about how extreme weather impacts human health.

Q: How do cold temperatures impact the body during short and long periods of time?
Dr. Onello
: In many cases, people can work and/or do recreational activities in very cold conditions provided that they have cold-appropriate attire (such as insulated clothing), can stay active and are able to avoid over-exposure by seeking shelter from the cold, if necessary. 

However, if someone is out in the cold and is not able to stay warm, several bodily reactions kick into action. These are called thermoregulatory responses. As skin cools, the body responds by vasoconstriction, or restricting warm blood flow to the colder regions to preserve the heat for the inner body core. This vasoconstriction response is most notable in limb extremities, such as fingers and toes, which are often susceptible to cold injury, such as frostnip and frostbite. 

During cold exposure, the body will also try to generate heat with an increase in metabolic activity, typically using skeletal muscle contractions. Voluntary muscle contractions occur as someone paces, jumps around or wiggles their limbs in an attempt to warm up. Involuntary muscle contractions occur as shivering, where much of the muscle energy is released as heat in an effort to stay warm.

Q: Can people still exercise or be outside for periods of time in the cold and heat?
Dr. Bianco
: The extremes of temperature and weather that we are now witnessing due to climate change has challenged those who exercise outdoors. Temperature regulation is a critical function of the body involving many complex internal processes. However, when challenged, the body can only do so much and becomes at risk for either hypothermia (low body temperature) or hyperthermia (high body temperature). By choosing the correct clothing, dressing in layers and increasing calories consumed, exercising in the severe cold can still be done safely. However, caution needs to be taken if exercising alone or in remote areas where an equipment failure or injury could put one at risk. 

On the other extreme, higher temperature and humidity is more challenging. Exercise intrinsically increases the body’s core temperature and its regulation is highly dependent on hydration, which is critical for cooling. Further, lightweight and loose fitting clothing helps with heat dissipation. Most importantly, knowing one’s level of fitness and not exhausting oneself is vital for safety, whether the temperature is hot or cold. 

Q: Who is most affected by extreme weather and how can they be helped?
Dr. Bianco
: For some athletes, cold weather breathing can lead to exercise-induced asthma. The airway, when exposed to cold as well as low humidity, excessive drying of the airway occurs leading to the spasming of the airway. Bronchodilator medications used before or during exercise can be preventative. For some, air warming masks may also help.

Temperature extremes currently are challenging public health in a number of ways. Food and water resources are challenged by drought, leading to shortages in both. Floods compromise water treatment facilities and sewage management. Wildfires threaten infrastructure. Increased cold weather extremes in southern climates challenge power grids, as we saw in Texas last year, leading to a number of deaths due to hypothermia. Even in northern climates, extreme prolonged cold weather impacts families due to increased heating costs, challenging their financial resources. It is not uncommon for patients to have to choose between paying for their medicines or paying for their heat. Planning for these extremes and their consequences is a public health and government challenge. Worldwide, climate extremes poise even greater challenges and disproportional mortality due to the lack of infrastructure and economic resources. 

We are beginning to recognize the importance of people having a roof over their head as a critical healthcare intervention. People who are homeless are the most exposed to extremes of climate change. Addressing homelessness and housing instability is, now more than ever, part of the conversation for preventive healthcare. Climate extremes have brought this to the forefront as nations have seen increased morbidity and mortality due to poor housing or homelessness. Research continues in regards to showing that medical costs go down when people are sheltered and their housing is stable. This is not only true for weather-related illness and injury but also for other chronic diseases. Safe and affordable housing in the past had not been recognized as a major healthcare intervention. More data and research is needed to identify at-risk populations and provide upstream interventions to mitigate the effects of climate extremes on the homeless. 

Q: As we enter spring, do large variations in changing temperature impact people’s health more than before?
Dr. Onello
: Though many people associate the problems of climate change with excessive or increasing heat, we know that a changing climate can also result in more temperature extremes and atypical cold spells. Population research data support the idea that human health suffers towards the extremes of temperature, both heat and cold. Studies reveal that cold temperatures, such as a cold spell lasting several days dipping below the expected temperature for a given location during wintertime, can increase the relative risk of cardiovascular mortality in that community. The increase in cardiovascular deaths associated with colder temperatures begin to be observed when temperatures decrease below 59 degrees Fahrenheit (not very cold by Minnesota standards!). 

Our warming planet can create increased temperature swings, or temperature variability, throughout the year. An emerging body of research is exploring the impacts of increased temperature variability on human health. Concerningly, population studies find negative human health effects associated with increasing temperature variability. For example, one study in Australia showed that temperature variability was associated with an increased mortality risk, separate from the risks associated with exposures to heat and cold. Though Minnesotans are certainly used to abrupt weather changes during our spring months, it is possible that increasingly variable temperatures may have new and concerning effects on our health. 

Q: What are you doing to further our understanding of how extreme cold and other effects of climate change impacts our health?
Dr. Onello
: Many of our state’s physicians and other health professionals, along with many health professional students, are concerned about the severity and complexity of the health impacts resulting from extreme climate events and our changing climate. However, not all of Minnesota’s healthcare professionals are aware of or agree about the urgency of the situation. Many may not recognize how climate change ‘shows up’ in our 1-on-1 encounters with patients. 

I am currently serving on an advisory panel for researchers at the Minnesota Department of Health (MDH). The research is aimed at characterizing the attitudes and experiences of Minnesota’s health professionals regarding patient encounters influenced by climate-related factors (e.g. worsening allergies, wildfire smoke-induced asthma exacerbations, emotional distress from crop/farm losses). Results from this ongoing MDH research project will assist the MDH and other agencies in developing new and effective educational materials for physicians and other health professionals. Such targeted educational programming can support health professionals who intervene with at-risk patients and families to establish healthcare plans that anticipate and/or mitigate the health risks from climate change-related circumstances. 

Dr. Onello is an assistant professor in the Department of Family Medicine and Biobehavioral Health at the U of M Medical School, Duluth Campus. Her research interests include rural physician workforce challenges, vaccination attitudes and environmental health. She has practiced as a family physician at Bay Area Health Center in Silver Bay and Lake Superior Community Health Center in Duluth. She is also a member of Health Professionals for a Healthy Climate, Northern Chapter. 

Dr. Bianco is an assistant professor in the Department of Family Medicine and Biobehavioral Health at the U of M Medical School, Duluth Campus. He is a director of primary care at Essentia Health and is a family physician in Ely.


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