Dr. Junya Shimazaki, a lecturer in Emergency Medicine at Kansai Medical University, offers strategic prevention advice for heatstrokes. He emphasizes the importance of proper hydration and electrolyte replenishment, as well as recognizing temperature differences between outdoor and indoor environments. Protecting vulnerable groups like children and the elderly is key. Additionally, preparing for summer by gradually acclimating to heat and building heat tolerance is crucial for comprehensive prevention.
1. Outdoor Protection: Avoid Direct Sunlight
The highest risk outdoors comes from direct sun exposure. Wear hats, choose well-ventilated clothing, and stay in shaded areas. Carry a parasol if possible. Avoid tight or heavy clothing; light colors (e.g., white) reflect heat better than dark colors (e.g., black).
2. Indoor Protection: Beware of Window Heat and Use Air Conditioning
Heat levels vary significantly within a room. Sun-facing windows are high-risk zones; even hospitalized patients have developed heatstroke from sitting too long by a window. Install blackout curtains or blinds to block direct sunlight.
Regarding ventilation: If outdoor temperatures are not extreme, opening windows helps with airflow. However, when outdoor temperatures soar to 35°C or 40°C – exceeding body temperature – open windows bring hot air in, not out. In midsummer, using air conditioning is beneficial and safe; do not hesitate to turn it on to save electricity.
3. Child Protection: Monitor Sweat and Urination
Children have a larger body surface area relative to weight, making them absorb heat faster. Their sweating mechanisms are immature. Adults must be proactive:
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If a child feels hot to the touch, move them to a cool place, stop activity, and cool them down.
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Children may not ask for water even if thirsty. Regularly remind them to drink before, during, and after activities.
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Urination frequency is a key indicator. No urination for half a day signals severe dehydration. Dark yellow, small amounts of urine also indicate fluid insufficiency.
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If a child stops sweating despite being in a hot environment, their cooling system has failed – this is a medical emergency. Children deteriorate faster than adults; immediate cooling and hydration are critical. Similarly, the elderly and those with limited self-care ability need regular offers of water and monitoring.
4. Strategic Hydration: Drink Morning and Before Exercise
The body loses fluids through sweat during sleep. Start the day with water; hydrate before exercise; drink small amounts frequently during rest periods. Build a habit of drinking proactively, not waiting for thirst.
Under normal diet conditions, most exercise does not require extra salt. Salt deficiency typically occurs when people drink large amounts of plain water after heavy sweating, diluting sodium (water intoxication). Choose sports drinks or oral rehydration solutions (properly balanced water, salt, and sugar) instead of plain water. If drinking plain water or tea for extended periods, pair it with salty foods.
5. Heat Acclimatization: Build a Sweating Habit Before Peak Summer
To stay healthy in summer, try "heat acclimatization" in early summer – gradually letting the body adapt to heat. Once adapted, sweating becomes more efficient: sweat volume increases, but salt concentration decreases, allowing faster cooling with less salt loss.
The key is "active sweating." Before extreme heat arrives, do moderate low-intensity exercise (e.g., brisk walking) daily to sweat lightly, helping the body "remember" how to sweat. Staying in air conditioning all day prevents adaptation. However, even after acclimatization, unlimited activity in high heat is still unsafe.
6. Lifestyle: Adequate Sleep and Avoiding Alcohol Excess
Building heat resilience starts with regular routines: adequate sleep, regular meals, and frequent small sips of water are the three pillars. Studies show that insomnia, sleep deprivation, or skipping breakfast significantly increase heatstroke risk under similar activity levels. Start each day with a glass of warm water.
Be mindful of alcohol: it is a strong diuretic. Drinking beer or spirits may seem hydrating but actually accelerates fluid loss. Avoid heavy drinking the night before outdoor activities, and drink extra water after consuming alcohol. Those with chronic conditions should consult their family doctor for summer hydration and activity guidelines.
