HEAT AND HEALTH

The current heat waves in Botswana are due to the combination of the sad reality of climate change and the El Nino Phenomenon.

The 2023/24 hot season has been described as a strong El Nino event, characterised by extreme heat and scanty rainfall. Extended periods of high day and nighttime temperatures create cumulative physiological stress on the human body, which exacerbates the top causes of death, including respiratory and cardiovascular diseases, diabetes mellitus and renal disease. Heatwaves can acutely impact large populations for short periods of time and often trigger public health emergencies.

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.

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 compromise 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 hospitalisations 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 diseases and diabetes-related conditions.

Heat also has important indirect health effects. Heat conditions can alter human behaviour, the transmission of diseases, health service delivery, air quality, and critical social infrastructure such as energy, transport, and water. The scale and nature of the health impacts of heat depend on the timing, intensity and duration of a temperature event, the level of acclimatisation, and the adaptability of the local population, infrastructure and institutions to the prevailing climate.

What actions should the public take?

Keep your home cool • Aim to keep your living space cool. 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

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 wet towels to cool down the room air. Note that the humidity of the air increases at the same time. If your residence is air conditioned, close the doors and windows and conserve electricity not needed to keep you cool, to ensure that power remains available and reduce the chance of a community-wide outage. • Electric fans may provide relief, but when the temperature is above 35 °C, may not prevent heat-related illness. It is important to drink fluids. •

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 where available). • 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 5:00 and 9:00. • 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. An umbrella is equally handy. • 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

Help others

• Plan to check on family, friends, and neighbours who spend much of their time alone. Vulnerable people might need assistance on hot days. If anyone you know is at risk, help him or her to get advice and support. Elderly or sick people living alone should be visited at least daily. If a person is taking medication, ask the treating doctor how it can influence thermoregulation and the fluid balance. • •

If you have health problems

• Keep medicines below 25 °C or in the refrigerator (read the storage instructions on the packaging). • Seek medical advice if you are suffering from a chronic medical condition or taking multiple medications.

If you or others feel unwell

• Try to get help if you feel dizzy, weak, anxious or have intense thirst and headache; move to a cool place as soon as possible and measure your body temperature. • Rest immediately in a cool place if you have painful muscular spasms (particularly in the legs, arms or abdomen, in many cases after sustained exercise during very hot weather), and drink oral rehydration solutions containing electrolytes. Medical attention is needed if heat cramps last more than one hour.