Extreme heat and health | Harvard T.H. Chan School of Public Health

July 15, 2026 - 04:16

As temperatures climb to dangerous levels across many regions, public health experts are warning that extreme heat is not just uncomfortable-it can be deadly. Heat-related illnesses, from heat exhaustion to life-threatening heatstroke, are on the rise during prolonged heat waves. According to researchers at the Harvard T.H. Chan School of Public Health, the human body struggles to cool itself when humidity is high and nights offer little relief, putting strain on the heart, kidneys, and brain.

Older adults, young children, outdoor workers, and people with chronic conditions face the highest risk. But even healthy individuals can suffer if they overexert themselves in the heat or fail to hydrate properly. Experts emphasize that heatstroke can set in quickly, with symptoms like confusion, hot dry skin, and a rapid pulse requiring immediate medical attention.

To stay safe, officials recommend drinking plenty of water, avoiding strenuous activity during peak afternoon hours, and never leaving people or pets in parked cars. Seeking air-conditioned spaces, even for a few hours a day, can make a critical difference. Simple steps like wearing light clothing, using fans wisely, and taking cool showers also help. As climate change drives more frequent and intense heat events, understanding these risks and preparing ahead becomes essential for communities everywhere.