Did you know that soaring temperatures can trigger or exacerbate health issues? In this new post, the Toronto Functional Medicine Centre sheds light on: 

• • What urban heat stress is;
  • How it can instigate health challenges;
  • And the ways extreme city heat is related to global warming. 

Understanding Urban Heat Stress

Urban heat stress refers to the physical strains experienced by people in cities from elevated temperatures, especially during heatwaves. It’s exacerbated by the Urban Heat Island (UHI) effect, a phenomenon in which cities are significantly warmer than surrounding rural areas.

Urban heat is enhanced by: 

• • Climate change: Extreme heat shifts in temperatures and weather trends driven by the increased use of fossil fuels, gasses, etc. 
  • Urbanization: When additional people move to cities, it causes declines in natural surroundings (i.e. vegetation, soil). New buildings and roads tend to absorb and release heat, too, which contributes to the UHI effect. 

The constituents listed below can also contribute to the severity of urban heat stress: 

• • Heat-absorbing materials: Concrete, asphalt, and buildings trap and radiate heat.
  • Lack of vegetation: Few trees mean less shade and less evaporative cooling.
  • Waste of heat: Air conditioners, vehicles, and factories release additional heat.
  • Dense infrastructure: Tall buildings reduce air circulation and trap heat at street level.

Heat has noticeably amplified in our country, even affecting the lifespan of Canadians. However, understanding the effects of urban heat stress can help us make informed decisions for ourselves and our loved ones. 

Health Consequences

Extreme city heat comes with an array of challenges, affecting the physical and mental performances of adults and children. In fact, “A U.S. study of mental health-related emergency department visits found an 8% increase in mental health visits on the hottest days of summer compared with the coolest days,” confirms the American Psychological Association. Urban heat stress can also cause or worsen:

• • Heat exhaustion and heat stroke
  • Dehydration
  • Respiratory distress (especially in those with asthma or COPD)
  • Heart attacks 
  • Poor sleep, fatigue, and mental stress
  • Increased mortality, especially in vulnerable groups (elderly, infants, outdoor workers)

If you’re diagnosed with a chronic condition (i.e. diabetes or heart disease), it’s to your advantage to speak to a functional health provider on keeping cool with your condition. Lifestyle modifications may be advised, too, such as optimizing hydration with IV therapy, installing additional fans in your home, and using an umbrella on sunny days.  

Environmental Impacts

It should also be noted that global warming exacerbates urban heat stress, and poorly designed cities intensify the impact of climate change. Urban heat stress is directly linked to global warming — and the two problems amplify each other: 

• • Global warming increases baseline temperatures: Climate change due to greenhouse gas emissions boosts average global and regional temperatures. In turn, heatwaves become frequent, intense, and longer-lasting in busy cities. 

• • Urban areas trap more heat: These environments tend to absorb/retain heat due to the asphalt and concrete streets. This contributes to the UHI effect, and can cause cities to be hotter than rural areas by 5-10°C.

When high global temperatures are paired with urban infrastructures, the risks of forming heat-related illness, energy overuse, and air pollution sharply increase. This combined effect “feeds” into the severity of urban heat stress – but there are ways to help reduce excessive city heat:

• • Speak to local leaders about adding green roofs, planting more trees, or adjusting city layouts for improving ventilation and shade.
  • If you’re planning for outdoor renovations, look into reflective building materials.
  • Visit your local cooling centres.
  • Listen to warning systems or the news to prepare for high heat (i.e. make sure you have enough drinking water at home, shade, etc.)

Suggested reading: Endometriosis: A Health Profile from Our Toronto Centre for Functional Medicine

Taking Action with Functional and Integrative Medicine

Urban heat stress and other environmental factors (i.e. mold) can take a toll on your health status. At the Toronto Functional Medicine Centre, we modify treatment options for your symptom relief and to help prevent the formation of chronic conditions. In fact, a comprehensive approach to wellness is valuable for managing long-term health needs, as well as food sensitivities, chronic pain, menopausal symptoms, and tissue repair. 

Our clinicians adhere to the functional medicine model. This paradigm focuses on individuality, helping to address the root cause of health concerns with tailored strategies, while supporting your natural healing process. These treatments are personalized based on unique constituents, such as medical history, genetics, nutrient deficiencies, lifestyle factors, environmental exposures, results from functional lab tests, and more. 

Each treatment modality from our clinic – including doses of IV therapy and herbal medicine – is customized with the principles of functional medicine. As our naturopathic doctor is trained in pharmacognosy (the study of medicinal derivatives), we can safely combine remedies while helping to avoid medication interactions. We are able to integrate conventional medicine practices with natural therapies (i.e. naturopathic medicine and homeopathic medicine), IV therapy, psychotherapy (lifestyle counselling), Traditional Chinese Medicine, Amazonian herbal remedies, hormone optimization programs (i.e. bioidentical hormone therapy), and more. Especially when it comes to getting intravenous therapy, our treatments are not meant to replace daily healthy habits. When combined with additional functional medicine therapies, as well as balanced eating and exercise, they can support health promotion. 

Just so you know, we’re a patient-centred practice. We encourage you to collaborate with our health providers while your treatment plan is being drafted. We embrace this unique partnership because it provides patients with additional knowledge and confidence in reaching optimal health results. Please don’t hesitate to ask our wellness team any questions!

Are you concerned about exposures to environmental toxins? Take preventative health measures with bespoke functional medicine therapies in Toronto. Simply click here to send us a request your first appointment with us.

Disclaimer: The information in this article is designed for educational purposes only and is not intended to be a substitute for informed medical advice or care. This information should not be used to diagnose or treat any health problems or illnesses without consulting a doctor. You should always consult with a health care practitioner before relying on any information in this article or on this website. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of information you have read from the Toronto Functional Medicine Centre website or other affiliate media. 

 

References

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Berry, P., Clarke, K., Fleury, M.D. and Parker, S. (2014): Human Health; in Canada in a Changing Climate: Sector Perspectives on Impacts and Adaptation, (ed.) F.J. Warren and D.S. Lemmen; Government of Canada, Ottawa, ON, p. 191-232.

Chen, Kaiyu, et al. “A Multiscale Analysis of Heatwaves and Urban Heat Islands in the Western U.S. during the Summer of 2021.” Scientific Reports, vol. 13, no. 1, 2023, pp. 1-12, https://doi.org/10.1038/s41598-023-35621-7. Accessed 4 Jun. 2025.

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Gronlund, Carina J. “Racial and Socioeconomic Disparities in Heat-related Health Effects and Their Mechanisms: A Review.” Current Epidemiology Reports, vol. 1, no. 3, 2014, p. 165, https://doi.org/10.1007/s40471-014-0014-4. Accessed 4 Jun. 2025.

“Heat and health” from the World Health Organizatin (WHO), posted May 28, 2024, viewed on June 5, 2025. 

“Heat Waves, Heat Islands, and Your Health” from the National Environmental Education Foundation (NEEF), posted on August 1, 2023, viewed on June 4, 2025. 

“How Cities Around the World Are Tackling the Urban Heat Crisis” from Earth.Org, posted June 4, 2024, viewed on June 4, 2025. 

“How heat affects the mind” from the American Psychological Association, posted on June 1, 2024, viewed on June 5, 2025. 

Hsu, Angel, et al. “Disproportionate Exposure to Urban Heat Island Intensity across Major US Cities.” Nature Communications, vol. 12, no. 1, 2021, pp. 1-11, https://doi.org/10.1038/s41467-021-22799-5. Accessed 4 Jun. 2025.

Huang, Huanchun, et al. “Urban Heatwave, Green Spaces, and Mental Health: A Review Based on Environmental Health Risk Assessment Framework.” Science of The Total Environment, vol. 948, 2024, p. 174816, https://doi.org/10.1016/j.scitotenv.2024.174816. Accessed 4 Jun. 2025.

Marginean, I., et al. “High-Resolution Modeling and Projecting Local Dynamics of Differential Vulnerability to Urban Heat Stress.” Earth’s Future, vol. 12, no. 10, 2024, p. e2024EF004431, https://doi.org/10.1029/2024EF004431. Accessed 4 Jun. 2025.

“Reducing Urban Heat Islands to Protect Health in Canada” published by Health Canada, March 2020, viewed on June 4, 2025. 

Tong S, Prior J, McGregor G, Shi X, Kinney P. Urban heat: an increasing threat to global health BMJ 2021; 375 :n2467 doi:10.1136/bmj.n2467

“What is the urban heat island effect?” from American Forests, posted on September 25, 2020, viewed on June 5, 2025.