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Warnings about hot weather are not being heard by people at risk. Most do not see themselves as vulnerable to heat, and do not take action to protect themselves. A recent survey found they are more likely to protect themselves against sunburn during heatwaves, than against heat.

Heat exhaustion can mean a headache, dizziness, and loss of appetite. If the person can be cooled down within 30 minutes, it is not usually serious. But if not, they may develop heatstroke and need emergency treatment. Signs of heatstroke include confusion, a fit (seizure) and loss of consciousness.

People over 75 are especially vulnerable to heat-related illness as they cannot adapt to changing temperatures as well as younger people. Other groups at risk include people with long-term conditions such as heart disease or diabetes, and those who use drugs or alcohol.

The Heatwave Plan for England advises people to adopt health protection behaviours during hot weather. The survey found that, during a heatwave in 2017, most people over 75 (64%) heard the health advice issued, but few (27%) changed their behaviour. Drinking cool fluids, and opening windows at night were the most common behaviour changes. Closing windows exposed to the sun or using an electric fan were the least.

Focus groups helped explain some of the findings. The noise and cost of electric fans discouraged their use, for example. And many people believed that windows should be kept open to let the air circulate.

Researchers say that messages about the potential dangers of heatwaves, and the best ways to protect against them, need to be strengthened. They need to be adapted for the people most at risk of harm.

Further information about heat exhaustion and heatstroke is available on the NHS website.

What’s the issue?

Heatwaves are expected to become more common as a result of climate change. During the severe heatwave of 2003, there were 2,000 more deaths than expected. As a result, the Heatwave Plan for England was developed. When temperatures reach approximately 30 degrees during the day and 15 degrees at night, warnings are issued, and advice is given on how to adapt to the heat.

Those most at risk include older adults (over 75 years), especially those living alone who are socially isolated. The very young, and people with other long-term conditions such as diabetes or heart conditions are also at high risk, along with people who are homeless, and those who use drugs or alcohol. Living in built-up areas increases the risk.

Researchers wanted to find out how effective the Heatwave Plan for England is. Their overall evaluation included surveys of the public and professionals; analysis of heat health data for the years before and after the Plan was implemented; and case studies in several local authorities in England, which looked at how the plan was implemented.

What’s new?

This study, which was part of the overall evaluation of the Heatwave Plan, explored the views of people who are vulnerable to heat. It was based on a survey completed by 1,872 adults, who were selected to be representative of the general population in England. Researchers also held 5 focus groups with lunch clubs or voluntary groups aimed at older people, to gather the views of people who are vulnerable to heat.

Survey respondents were grouped according to their vulnerability to heat. The vulnerable group included everybody aged 75 and over.

Overall, most people (58%) said they loved hot weather; this fell to half (49%) of the over 75s. Few of the overall group (31%) thought that hot weather posed a risk; even among the over 75s, less than half (42%) saw themselves as vulnerable.

A heat health alert was issued during a heatwave in 2017. The survey found that, overall, half (49%) had not heard the advice given. More (64%) over 75s had heard the advice, but few (27%) of this group changed their behaviour as a result. Unsuprisingly, they were more likely to make changes they believed to be effective.

The Heatwave Plan recommends 9 actions to protect health. The over 75s reported which of these actions they took during the 2017 heatwave:

  • drinking cool fluids (81% people)
  • opening windows at night (78%)
  • limiting physical activity (72%)
  • covering skin (65%)
  • avoiding alcohol (63%)
  • staying out of the sun between 11am and 3pm (59%)
  • closing curtains on exposed windows (55%)
  • closing windows exposed to the sun during the day (52%)
  • using an electric fan (31%).

The focus groups added nuance. Older people did not realise their age made them less able to adapt to the heat. They thought they knew what action to take in a heatwave because it was ‘common sense’.

Some kept their windows closed at night because of worries about break-ins, and said they were prepared to accept short-term discomfort for security. Cost of electricity and noise put people off using electric fans. People thought windows should be open during the day, even if they were in the sun, to let air circulate. They often did not realise how hot the room had become until visitors mentioned it.

People were more concerned about sunburn, because of the risk of skin cancer, than about heat. Some older people said they did not drink extra fluids, because they said they were not thirsty or disliked drinking water.

Why is this important?

The research suggests that current messages about the dangers of hot weather are not getting through. Even vulnerable people who had heard the health advice were unlikely to take all the actions they could to protect themselves during a heatwave.

Participants often spoke about the effects of the sun on skin. This reflects public health messages about skin cancer. Many believed that as long as they stayed indoors or in the shade, they were not at risk.

Public health messages need to be changed, and make clear that older people are vulnerable to heat (and not just to the sun). Many older people do not recognise their own vulnerability and do not know that they need to take action to reduce their risks.

Most vulnerable people were not aware that closing windows exposed to sunlight during the day could help them cope with heat. Advice on using an electric fan and avoiding alcohol was unknown by most of this group.

Stronger messages about these measures, and how effective they are, could encourage people to use them.

What’s next?

Climate change is likely to mean increasingly warm summers in England. This means vulnerable people need to be convinced of the risks of hot weathers, and the importance of protecting themselves.

The researchers hope that public health authorities will take their findings on board. They would like the Heatwave Plan for England to strengthen the messages put out through public health channels. They need to make clear that people over 75 are at risk from heat. Many in this age group would not assume that messages aimed at 'vulnerable' people apply to them.

The health service more widely – such as primary care staff – are well-placed to educate people at risk about measures they can take.

You may be interested to read

This NIHR Alert is based on: Erens B, Williams L, Exley J, and others. Public attitudes to, and behaviours taken during, hot weather by vulnerable groups: results from a national survey in England. BMC Public Health 2021;21:1631

A study observing heatwave mortality in the summer of 2020: Thompson R, and others. Heatwave Mortality in Summer 2020 in England: An Observational Study. International Journal of Environmental Research and Public Health 2022;19:6123

Further information about the Heatwave Plan for England evaluation, including a blog and the in-depth report, can be found on the PIRU website.

Staying Cool in a Heatwave: Age UK’s free guide provides advice on how to protect yourself from the heat. For a free copy call Age UK Advice free on 0800 169 6565.

Funding: This work was funded by the NIHR Policy Research Programme.

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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Study author

People knew they were at risk outside, but they thought it was more about the risks of sunburn and skin cancer than heat problems. Generally speaking, this is true because England just doesn’t have many heatwaves. But heatwaves do present a problem, and this is going to increase with climate change, so it’s very important that messages around heat start cutting through to vulnerable people.

We found that they weren’t taking protective actions inside during the heatwave. They were either ignoring warnings or thought they weren’t relevant to them. What was coming across was that people were taking risks in their own homes.

It is all about messaging. Most of the Heatwave Plan relies on people changing behaviour, so it is reliant on public health messaging. The message has to focus more on heat rather than sun. That’s clearly not getting across.

Lorraine Williams, Research Fellow, Policy Innovation and Evaluation Research Unit (PIRU), and Bob Erens, formerly deputy director, PIRU, London School of Hygiene and Tropical Medicine (now retired) 

Age UK 

This new research is welcome as it highlights how important it is that older people are aware of the risks of hot weather. The fact remains that our bodies become less able to cope with hot weather as we get older and while we should all be able to enjoy some sunshine it can put older people at a higher risk of things like heat exhaustion and heatstroke.

We advise remaining indoors during the hottest part of the day, wearing light clothing, drinking plenty of fluids and continuing to eat well during heatwaves to ensure the body replaces salt lost through sweat . It can also be helpful to have more cold foods, particularly salads and fruits which contain water.

During successive hot days it is important that older people are able to cool down in the evening and at night, so we advise keeping homes shaded and well ventilated. Anyone with an older family member or neighbour can help by calling in to check to see if they are ok and if they need help in taking reasonable precautions to stay well in the hot weather. When it’s hot, check they’re staying out of the sun, continuing to drink lots, and eating a balanced diet. Offer to go shopping or run errands for them, as this means they don’t have to go out into the extreme heat.

Caroline Abrahams, Charity Director, Age UK 

Royal Society for Public Health 

As many of us look forward to the summer months, we must be mindful that some will be more vulnerable to very hot temperatures than others. Pre-existing conditions such as diabetes and heart disease can elevate people’s health risk, as can demographic and socio-economic factors including older age and homelessness.

This study has shown that while a vulnerable person does generally recognise the harmful effects of exposure to UV rays, there is less understanding of the dangers of high temperatures. This results in a mismatch between environmental risks to health, public understanding, and people’s behaviour changes during heatwaves.

The RSPH is committed to supporting all communities to having better access to information and better health outcomes, and supports this call for clearer and consistent public health communication in the lead up and during heatwaves. In particular, messaging must be targeted at the more vulnerable groups. This is even more vital given that the growing prevalence of non-communicable diseases and climate change will continue to increase population vulnerability to heatwaves in the future.

Jyotsna Vohra, Director of Policy and Public Affairs, Royal Society Public Health (RSPH)  

Member of the public 

The research highlights the limitations of current public health messaging and should encourage research into more effective, impactful messaging, thereby potentially lowering excess deaths.

Louise Rowan, Public Contributor, Sutton Coldfield

Member of the public 

I hope this study will encourage all those responsible for implementing the Heatwave Plan – particularly the Department for Health and Social Care – to critically review and overhaul the design of any heat-health related behaviour change campaigns/messaging under their remit.

My grandmothers are in their 80s and therefore are vulnerable to the effects of heat, so I will pass these findings on to them.

Alexandra Chitty, Public Contributor, London


This work clearly demonstrates the lack of understanding and interest in heat-related health behaviours, particularly for vulnerable people. It shows that a better approach is needed to communicate heat-related health messages during heatwaves.

These findings closely follow some qualitative interviews my team did on heat-related behaviours in a retirement community. I would like to know more about the focus group sample, and about the areas participants came from.

Rachael, Researcher, London

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