HEAT AND ITS EFFECT

Population exposure to heat is increasing due to climate change, and this trend will continue. Globally, extreme temperature events are observed to be increasing in their frequency, duration, and magnitude.

 Between 2000 and 2016, the number of people exposed to heat waves increased by around 125 million. In 2015 alone, 175 million additional people were exposed to heat waves compared to average years.

Single events can last weeks, occur consecutively, and result in significant excess mortality. In 2003, 70 000 people in Europe died as a result of the June-August event, in 2010, 56 000 excess deaths occurred during a 44-day heatwave in the Russian Federation.

Exposure to excessive heat has wide ranging physiological impacts for all humans, often amplifying existing conditions and resulting in premature death and disability.

Who is affected?
Rising global ambient temperatures affect all populations. However, some populations are more exposed to, or more physiologically or socio-economically vulnerable to physiological stress, exacerbated illness, and an increased risk of death from exposure to excess heat. These include the elderly, infants and children, pregnant women, outdoor and manual workers, athletes, and the poor. Gender can play an important role in determining heat exposure.

How does heat impact health?
Heat gain in the human body can be caused by a combination of external heat from the environment and internal body heat generated from metabolic processes. Rapid rises in heat gain due to exposure to hotter than average conditions compromises the body’s ability to regulate temperature and can result in a cascade of illnesses, including heat cramps, heat exhaustion, heatstroke, and hyperthermia.

Deaths and hospitalizations from heat can occur extremely rapidly (same day), or have a lagged effect (several days later) and result in accelerating death or illness in the already frail, particularly observed in the first days of heatwaves. Even small differences from seasonal average temperatures are associated with increased illness and death. Temperature extremes can also worsen chronic conditions, including cardiovascular, respiratory, and cerebrovascular disease and diabetes-related conditions.

What actions should the public take?

• Keep your home cool.
• Aim to keep your living space cool. Check the room temperature between 08:00 and 10:00, at 13:00 and at night after 22:00. Ideally, the room temperature should be kept below 32 °C during the day and 24 °C during the night. This is especially important for infants or people who are over 60 years of age or have chronic health conditions.
• Use the night air to cool down your home. Open all windows and shutters during the night and the early morning, when the outside temperature is lower (if safe to do so).
• Reduce the heat load inside the apartment or house. Close windows and shutters (if available) especially those facing the sun during the day. Turn off artificial lighting and as many electrical devices as possible.
• Hang shades, draperies, awnings or louvers on windows that receive morning or afternoon sun.
• Hang wet towels to cool down the room air. Note that the humidity of the air increases at the same time.

Keep out of the heat

• Move to the coolest room in the home, especially at night.
• If it is not possible to keep your home cool, spend 2–3 hours of the day in a cool place (such as an airconditioned public building).
• Avoid going outside during the hottest time of the day.
• Avoid strenuous physical activity if you can. If you must do strenuous activity, do it during the coolest part of the day, which is usually in the morning between 4:00 and 7:00.
• Stay in the shade.
• Do not leave children or animals in parked vehicles.

Keep the body cool and hydrated

• Take cool showers or baths. Alternatives include cold packs and wraps, towels, sponging, foot baths, etc.
• Wear light, loose-fitting clothes of natural materials. If you go outside, wear a wide-brimmed hat or cap and sunglasses.
• Use light bed linen and sheets, and no cushions, to avoid heat accumulation.
• Drink regularly, but avoid alcohol and too much caffeine and sugar.
• Eat small meals and eat more often. Avoid foods that are high in protein.