Climate change is primarily associated with rising temperatures, heatwaves and extreme weather events. However, its consequences are becoming increasingly visible in medical practice. High temperatures and air pollution can affect blood pressure, glucose metabolism and cardiovascular function. They can also make the treatment of people with chronic diseases more challenging.
An international team of experts, including Professor Donata Kurpas from Wroclaw Medical University, reviewed the current evidence on the impact of climate change on cardiovascular risk factors. The paper was published in the European Journal of Preventive Cardiology. The experts point out that environmental conditions, including heat, air quality and noise, are becoming increasingly important in cardiovascular risk assessment. Older adults and patients with chronic diseases require particular attention.
What happens to the heart during hot weather?
The human body tries to maintain a stable temperature. When it gets hot, blood vessels in the skin dilate, blood flow increases, the heart starts working faster, and sweating helps the body release excess heat. At the same time, we lose water and electrolytes.
For a healthy person, this is usually a strain that the body can cope with. The situation may be different for someone with heart disease, hypertension, diabetes or chronic kidney disease.
The impact is more direct than it might seem. During hot weather, the body has to work hard to release heat. In a patient with heart disease, hypertension, diabetes or chronic kidney disease, this additional strain can disrupt the body’s existing balance, explains Professor Donata Kurpas.
Dehydration reduces circulating blood volume and can lead to a drop in blood pressure and electrolyte disturbances. This increases the risk of cardiac arrhythmias, myocardial ischemia or worsening heart failure. Prolonged exposure to high temperatures may also exacerbate inflammation, oxidative stress and endothelial dysfunction. The endothelium is the inner layer of blood vessels.
Air quality also matters
Another important threat is air pollution. Environmental conditions are becoming another element of cardiovascular risk assessment, alongside smoking, diet, physical activity and comorbidities.
Air pollution, particularly fine particulate matter PM2.5, is not only a respiratory problem. It triggers inflammation and oxidative stress, affects endothelial function, and can impair blood pressure control and increase the risk of cardiovascular events. Importantly, high temperatures and air pollution can amplify each other’s effects, says Professor Donata Kurpas.
Who should be particularly careful?
Older adults are particularly vulnerable to the effects of heat. As we age, the body’s ability to regulate temperature declines: sweating and the sensation of thirst weaken, while the cardiovascular system has a harder time adapting to high temperatures.
Comorbidities, medications, functional status and living conditions also matter. Particular attention should be paid to people with cardiovascular disease, heart failure, diabetes and chronic kidney disease, as well as patients taking multiple medications.
During a heatwave, the level of risk depends not only on how high the temperature is, but also on whether a person can stay adequately hydrated, cool their body and quickly obtain help if their health deteriorates, Professor Kurpas emphasizes.
Symptoms that should not be ignored include severe weakness, dizziness, fainting, palpitations, shortness of breath, chest pain, altered consciousness, a significant drop in blood pressure or a marked decrease in urine output. People with diabetes should also pay attention to sudden deterioration in glycaemic control.
Heat can affect the safety of treatment
In patients treated for chronic diseases, high temperatures can affect the safety of pharmacotherapy. This applies particularly to medicines that influence fluid and electrolyte balance, blood pressure, kidney function or thermoregulation.
Diuretics increase fluid loss and may therefore contribute to dehydration, electrolyte disturbances and low blood pressure during hot weather. Patients taking ACE inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists or SGLT2 inhibitors also require particular attention during periods of high temperatures. Some beta-blockers may, in turn, limit physiological thermoregulatory mechanisms. This does not mean, however, that patients should reduce the dose or stop taking their medication on their own.
Patients should not modify their medication on their own. Suddenly stopping some antihypertensive drugs can be just as dangerous as continuing them at an unchanged dose in a person who is dehydrated and has significantly low blood pressure, Professor Donata Kurpas points out.
Any treatment change requires an individual assessment. The physician considers factors including blood pressure, hydration status, kidney function, comorbidities and current medication. Patients at particularly high risk should discuss with their physician in advance what they should monitor during a heatwave and which symptoms should prompt them to seek medical advice.
Medication storage conditions are also important. High temperatures and humidity can affect the stability of some medicines, so follow the manufacturer’s storage recommendations. This applies, among other things, to insulin.
How can the risk be reduced?
The most important thing is to act before symptoms of overheating or dehydration appear. In hot weather, limit strenuous physical activity during the hottest part of the day. Plan exercise for cooler times and in locations away from busy roads. When air quality is particularly poor, move physical activity indoors. It is also important to ensure access to a cool environment and to drink fluids regularly, unless a physician has recommended fluid restriction.
People treated for hypertension should check their blood pressure more frequently during hot weather, while patients with diabetes should monitor their blood glucose levels. In people with heart failure, fluid intake should be determined individually.
Chest pain, sudden shortness of breath, fainting, altered consciousness or symptoms that may indicate a stroke require urgent medical attention, regardless of temperature or air quality.
Prevention does not end with the patient
The authors emphasize that adapting healthcare to climate change cannot rely solely on providing patients with additional recommendations. Heat and air pollution early warning systems, appropriate urban planning, education of healthcare professionals and continuity of care during extreme weather events are also needed.
The publication is a non-systematic narrative review prepared by an interdisciplinary team of experts who reached consensus on its content. The authors emphasize that although evidence linking environmental factors with cardiovascular risk is growing, many areas still lack intervention studies that would allow the effectiveness of specific preventive strategies during heatwaves and periods of high air pollution to be assessed precisely.
Heat and smog. How can you protect your health?
During hot weather:
- drink fluids regularly, unless your doctor has advised you to restrict your fluid intake,
- avoid strenuous exercise and spending long periods outdoors during the hottest part of the day,
- keep your body cool whenever possible,
- if you have hypertension, check your blood pressure more frequently,
- if you have diabetes, check your blood glucose levels more frequently,
- watch for weakness, dizziness, fainting, palpitations and shortness of breath,
- do not change the doses of your medications or stop taking them without consulting your doctor,
- check the recommended storage conditions for your medications, especially insulin.
When air quality is poor:
- check current air quality alerts,
- limit prolonged physical activity outdoors, especially near busy roads,
- choose a different time or location for physical activity,
- when air pollution is very high, consider exercising indoors.
Seek urgent medical attention if you experience chest pain, sudden shortness of breath, fainting, altered consciousness or symptoms that may indicate a stroke.