The current weather forecast suggests summer might finally have arrived, as the UK’s first of the year has been issued.
Author
Adam Taylor
Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University
While many may be rejoicing after the UK’s miserable spring, it’s worth remembering that hot temperatures can be dangerous. Heat stroke is a risk for anyone – though the elderly and people with underlying health conditions are .
Certain health conditions can also be made worse when it’s hot outside. So if you’re someone who has a heart, lung, kidney or metabolic condition, it’s worth being extra careful during the hot weather.
Heart conditions
Many cardiac conditions become worse during hot spells because the cardiovascular system has to work harder than usual. This is because it plays an important role in the body’s built-in cooling processes. The heart helps move heat away from vital systems, and brings blood to the skin’s surface in order to cool it down.
As such, the heart during hot weather – beating up to per minute for every 1°C temperature increase. Blood flow to the skin is also increased to , which also spikes the heart rate in order to try and cool the body.
People of course also during hot weather so the body can cool itself. But if they don’t fluid, this results in thicker blood. This, too, means the heart has to work harder.
All of these changes can worsen heart condition symptoms.
For example, people with heart failure may find hot weather particularly challenging. Cooling processes such as (widening of the blood vessels) are impaired by this condition. This makes the . People with coronary artery disease may also experience (angina) if they exert themselves during the hot weather, due to the added pressure of these cooling processes.
People with heart arrhythmias, particularly atrial fibrillation, are at during hot weather. A 1°C temperature increase, sees a significant – particularly in women, over-65s and those living in tropical climates or in lower-middle income countries.
Regardless of your specific condition, studies show that for every day of extreme heat, there’s a in the number of monthly deaths directly related to cardiovascular conditions.
Between 1990 and 2019, the number of heat-related cardiovascular disease deaths per year has increased from . Many other studies have shown .
Heat’s effects on the cardiovascular system can even be seen for after temperatures have fallen. This illustrates hot weather is for the body.
Respiratory conditions
Hot weather aggravates many respiratory conditions.
People with asthma made find their symptoms are worse when it’s hot. This is because hot weather increases the and in the air which irritate and inflame the lungs and blood vessels when they .
The poor air quality on hot days due to particulate matter and allergens also means people with chronic obstructive pulmonary disease are at increased risk of death during the hot weather. Studies have shown that even a single degree can worsen symptoms – leading to greater , and a .
Even people without a respiratory condition may find their when hot temperatures arrive. This may also be due to particulates in the air, and the diversion of blood to the skin to help cool us down.
Kidney conditions
The kidneys play a critical role in fluid and electrolyte balance. This means they come under increased strain during hot weather – especially if we become dehydrated. Dehydration makes blood thicker, making it harder to filter waste.
Dehydration also explains why hot weather can cause a 30% increase in morbidity . A rising global climate also makes more common.
The challenge is even greater for those on dialysis, who have a . People with kidney disease who live in hot climates may even see their kidney function compared to those living in temperate climates due to the added strain of heat on kidney function.
Metabolic conditions
People who are overweight or obese may struggle more in the heat as their body may not be able to remove heat . One reason for this is that, on average, they have a higher – the amount of calories needed to keep cells functioning. This means they’re already energy within their body without the extra pressure of hot temperatures outside. Their heart may also have to to keep their core body temperature cool.
People with diabetes are also at increased risk of heat-related illnesses. In the UK alone, the number of type 2 diabetics needing healthcare increases for .
Type 1 and type 2 diabetes impair the body’s as it reduces blood flow to the skin and sweating – both key in taking heat from the body.
High blood sugar as well. This can have a serious impact on how efficiently the body removes heat from the body.
To protect yourself, the best things to do are staying out of the sun during the hottest part of the day, (not alcohol) to replace what’s lost as sweat, (or lukewarm shower if you prefer) and a cool flannel on the forehead or back of the neck.
This all reduces the temperature of your blood when it goes back to the central organs, helping to reduce their core temperature and dissipate heat away from them.
Adam Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
