For most people, a hot summer’s day is uncomfortable. For someone with scarred lungs, it can become a medical risk.
People living with interstitial lung disease (ILD) are especially vulnerable during extreme heat. As climate change drives more frequent and intense heatwaves, people with ILD will need better protection from hot weather and related health risks.
ILD is an umbrella term for more than 200 lung conditions. These conditions cause inflammation, the body’s immune response to injury or irritation, and fibrosis, which means lung scarring. As scar tissue builds up, the lungs become stiffer and less able to transfer oxygen into the bloodstream, making breathing harder.
Many ILDs, particularly idiopathic pulmonary fibrosis (IPF) – a form of lung scarring that develops without a clear known cause – affect people over 65. Older adults with ILD often also live with other long-term conditions, such as heart disease, diabetes, high blood pressure or chronic kidney disease. These can reduce the body’s ability to cope with stresses such as extreme heat.
Hot weather forces the body to work harder to stay cool. The heart pumps more blood towards the skin, breathing can become more difficult, and oxygen demand may increase. For people with ILD, whose lungs already struggle to supply enough oxygen, this can lead to worsening breathlessness, fatigue and reduced exercise tolerance.
Dehydration, which is common during heatwaves, can cause weakness, dizziness or low blood pressure. This can be a particular problem for older adults taking medicines such as diuretics, often known as water tablets, which help the body get rid of excess fluid.
Heatwaves can also bring environmental hazards. Higher levels of ground-level ozone, a harmful air pollutant formed when sunlight reacts with emissions from vehicles and industry, can irritate the lungs. Wildfire smoke and airborne particles, meaning tiny pieces of pollution in the air, can also worsen breathing symptoms. A 2026 review concluded that these exposures may trigger flare-ups and could contribute to disease progression by increasing inflammation and biological processes linked to lung fibrosis.
Risk reduction
There are practical steps that can reduce the risks.
People with ILD should check local weather forecasts and heat-health alerts during hot weather. It can also help to make a simple plan: who to contact if symptoms worsen, where to go if the home becomes too hot, what to do during a power cut if using oxygen equipment, and how to get medical advice.
During extreme heat, people with ILD should avoid being outdoors during the hottest part of the day. For people with moderate to severe ILD, fatigue is often already a limiting factor. Essential activities are best planned for the early morning or evening, when temperatures are lower.
Keeping indoor spaces cool is equally important. Closing curtains or blinds during the day, improving ventilation during cooler evenings, and using air conditioning where available can help maintain a safer indoor temperature. Fans may also help some people manage breathlessness. A small pilot study of handheld fans in people with ILD found that some patients considered them useful for breathlessness relief, although they should not replace medical care. Where air conditioning is unavailable, public buildings such as libraries, community centres or shopping centres may provide a cooler refuge.
Staying hydrated is another important measure. Drinking water regularly helps replace fluid lost through sweating, although people with heart failure or kidney disease should follow advice from their healthcare team if they have fluid restrictions.
People with ILD should continue taking prescribed medications exactly as directed. Antifibrotic medicines, which are drugs used to slow lung scarring in some types of ILD, remain important during hot weather and should be stored according to the manufacturer’s recommendations.
Those using home oxygen should ensure they have an adequate supply. People who use an oxygen concentrator, a machine that takes oxygen from room air and delivers it through tubing, should know what to do during power cuts. Oxygen equipment should also be kept away from heat sources.
Some people with ILD use home spirometry to monitor lung function between clinic visits. Spirometry is a breathing test that measures how much air a person can blow out and how quickly. While home spirometry can provide useful information, it should not be interpreted in isolation, especially during a heatwave. Qualitative research has shown that patients value home spirometry but can find fluctuating results difficult to interpret without support. Heat, dehydration, fatigue or difficulty blowing out the fullest possible breath may also affect readings.
Instead of focusing on spirometry alone, people should pay attention to the bigger picture. Increasing breathlessness, needing more oxygen than usual, walking shorter distances, worsening cough, unusual fatigue or finding everyday activities more difficult may all be signs that the body is struggling with the heat. These changes should prompt discussion with a GP, specialist nurse or ILD team.
Because many people with ILD are older and may live alone, support from family members, neighbours and carers becomes important during heatwaves. A simple phone call or visit to check that someone is staying cool, drinking enough fluids and coping with symptoms can make a significant difference.
People should also know when to seek medical advice. Worsening breathlessness, increasing oxygen requirements, chest pain, confusion, fainting, fever or symptoms that do not improve with rest should never be ignored. Early assessment can help identify an exacerbation, also called a flare-up, which is a sudden worsening of the condition. Prompt treatment may help limit serious complications.
As the climate continues to warm, healthcare will need to adapt to protect people who are especially vulnerable to heat. Helping people understand environmental risks, prepare for extreme weather and recognise changes in symptoms will become an essential part of living well with ILD.
Anne-Marie Russell 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.
