By Sylvester Ojenagbon

Last week, the Nigerian Meteorological Agency (NiMet) predicted a prolonged heatwave across the country. The agency, in its weather outlook, hinted that maximum temperature reports across the country were mostly between 38 – 40℃. It stated that air temperatures were expected to stay within this band and rise slightly in some locations.

For many who have been wondering if the door of hell has been suddenly unsealed and turned in the direction of Nigeria, this is cause for concern. Rather than bring succour, the downpour in some parts of the country after that prediction seems to have exacerbated the already frightening situation.

Now, extreme heat is often associated with heatwaves. In Nigeria, it is considered to be temperatures exceeding 38°C. The exact threshold may however vary depending on the climate of the area. Extreme heat can also be described in terms of the heat index, which combines temperature and humidity to determine how hot it actually feels to the human body.

Among others, studies have shown that certain recent heatwaves would have been practically impossible without human-induced climate change. Trees and vegetation naturally help cool the environment through a process called transpiration. Unfortunately, deforestation has been the order of the day in many parts of the country. This, coupled with burning of fossil fuels, has significantly increased greenhouse gas concentrations in the atmosphere. This traps heat and raises average temperatures, thus making extreme heat events more frequent and intense. Climate change does not only raise baseline temperatures, it also amplifies natural temperature inconsistency.

In addition, urban areas tend to absorb and retain more heat due to extensive concrete and asphalt surfaces, inadequate vegetation, and high population density. Urban heat islands can cause temperature increases, especially at night, when heat is trapped in the built environment.

Beyond human factors, a climate phenomenon known as El Niño leads to warmer-than-usual sea surface temperatures in the Pacific Ocean. This affects global weather patterns and contributes to more intense heat in certain regions. La Niña, on the other hand, typically leads to cooler conditions. However, it can sometimes result in abnormal warming in specific areas, thus contributing to heatwaves.

These and other factors usually interact with and amplify one another, and lead to extreme heat situations that can have serious consequences for human health. Sadly, vulnerable populations like the elderly, young children, or people with pre-existing health conditions are often the most affected.

The truth is that prolonged exposure to high temperatures can lead to heat exhaustion. This is characterised by symptoms such as dizziness, nausea, heavy sweating, and fatigue. If not quickly addressed, this can progress to heatstroke, a life-threatening condition where body temperature exceeds 40°C and lead to organ failure and potential death.

Extreme heat also increases heart rate and blood pressure as the body works harder to cool itself. This strain can worsen existing cardiovascular conditions, increasing the risk of heart attacks and strokes.

High temperatures can similarly worsen respiratory problems, particularly in individuals with pre-existing conditions like asthma or chronic obstructive pulmonary disease (COPD). Heat-related stress can also lead to increased lung damage and respiratory distress due to higher levels of air pollution during heatwaves.

The dehydration caused by excessive heat can lead to acute kidney injury. This is because the kidneys are strained as they attempt to manage fluid balance. This can result in long-term damage if dehydration is severe.

Extreme heat can also impair cognitive function, leading to confusion and disorientation. It may equally increase the risk of mental health issues, impairing judgment and physical performance, thus raising the likelihood of accidents and injuries.

It is therefore important that you stay indoors, where possible, during the hottest parts of the day, which is typically between 10 a.m. and 4 p.m. This is when the sun’s intensity is at its peak. If you must be outside, take frequent covers in a shaded or cool area, and avoid strenuous physical activity as much as you can.

It is also important that you drink plenty of water throughout the day, even if you do not feel thirsty, and avoid alcohol, caffeine, and sugary drinks, as they can dehydrate you. It is also pertinent to eat foods with high water content, like fruits and vegetables, especially watermelon and cucumbers, to help keep yourself hydrated.

You should also be mindful of the clothes you wear in times of extreme heat. Lightweight, loose-fitting clothes made of natural fabrics like cotton can help your body stay cool. And it is better to avoid dark colours, as they can absorb more heat. You may consider wearing a wide-brimmed hat to protect your face and neck from the sun.

Wherever you are, quickly move to a cooler place, drink water, and rest once you start experiencing heavy sweating, weakness, dizziness, nausea, headache, and muscle cramps. It becomes a medical emergency the moment you start experiencing hot and dry skin, high body temperature above 39.4°C, rapid pulse, confusion, and unconsciousness. At that point, you are at the tipping point and so need to seek immediate medical help.

Ojenagbon, a health communication expert, lives in Lagos.