This week has brought the second heatwave of the year, and with it the increased risks to health, especially of the very young and very old in our community. While there are geopolitical questions around strategies to tackle climate change, which is assumed to be the underlying cause for the increased frequency of these temperature peaks, understanding the immediate health risks may help reduce illness, and even death, on a more local level.
Firstly, it is important to understand how the body works. Primarily, the proteins which carry out all the important processes in our body, that is, enzymes, can only function within a very narrow temperature range, between 34-40 degrees Celsius, but ideally around 37C. If the body’s core temperature deviates from that it upsets various other systems in the body and things can quickly spiral out of control. In hot weather therefore the brain, using information from temperature-sensing cells in the skin and other organs, and influenced by other factors such as dehydration or circulating chemicals in the blood released by muscle or inflammation, regulates temperature increases via two main mechanisms – vasodilatation (increased blood flow to the skin) and sweating.
Vasodilatation diverts blood from major organs to the skin, using it like a large radiator to lose heat from the body. This increases the demand on the heart to pump more blood but reduces the amount of blood flowing through the heart. To compensate, the heart beats faster and stronger, increasing the oxygen requirements of heart muscle. In people with heart disease this often results in a mismatch between oxygen demand and oxygen delivery, leading to angina or even a heart attack, or collapse.
Increased sweating, if fluid intake is inadequate, leads to dehydration which in turn causes heart strain, kidney injury or fainting, especially if people have heart problems or on certain medications. In addition, loss of salt (sodium) can lead to confusion or muscle twitching or seizures if extreme.
Certain medications are associated with higher risk of health problems in the heat. These include diuretics (water pills), blood pressure medication, antidepressants, medications used for incontinence (anticholinergics) and morphine-related painkillers such as codeine, tramadol or morphine. These compromise the body’s cooling mechanisms. Alcohol is a risk during heatwaves as it contributes to dehydration and alters behaviours to stay cooler.
People more at risk during these hot times are also those with mental health illness or living alone, not leaving the house, reduced mobility or confined to bed, as they are less likely to take measures to cool down.
In general, people over the age of 65 are more at risk of health problems in the heat, as they are more likely to be on medication or have underlying health problems such as diabetes, chronic obstructive pulmonary disease, kidney disease, stroke or heart disease. In addition, very young children under the age of two are more at risk as their bodies are more likely to absorb heat due to their higher relative body surface area and are dependent on adults ensuring they are not over exposed to warm clothing or heat. Unfortunately, most problems arise when they are left in hot cars for any length of time.
It shouldn’t be forgotten that heat stress can also affect younger healthy adults, especially athletes such as footballers (hence the hydration breaks we are seeing during the World Cup) or endurance runners, so it can be necessary to limit activities or take on extra fluids when it’s extra warm. Outdoor workers are also at risk, so regular breaks and hydration are important for them, as well as considering lighter clothing to avoid over-heating.
Although less of an issue on Guernsey, greater attention to ‘built environments’ in cities relates to the capacity of buildings to store heat during the day and prevent natural cooling of the air at night, leading to rising temperatures. This problem is also compounded by increased use of air conditioning, which pumps heat from inside buildings into the surrounding air and contributes to air pollution.
Hopefully over time measures to reduce global warming will have an impact – medical authorities are concerned that otherwise more preventable deaths will occur around the world. In the meantime, sensible measures should be taken during heatwaves which include:
Prevent prolonged direct sun exposure – keep to shaded areas
Wear loose, light clothing
Maintain regular hydration and limit alcohol intake
Ensure babies and toddlers are kept cool and encouraged to drink
If you are on medications mentioned above and feel unwell, consult your GP
Avoid over-exertion in the heat especially if you have a heart condition
Take regular breaks and adjust your fitness plans if you are exercising
And finally, look out for those around you who may be more at risk, especially elderly people living alone.
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