Millions of Britons face a higher risk of stroke or heart failure because of dirty air where they live.
People living in areas of the UK with the worst levels of air pollution are 27% more likely to develop heart failure, compared with people in areas with the cleanest air, a study suggests.
Stroke risk was 7% higher in the worst areas, the research shows. The findings were presented at the European Society of Cardiology conference in Madrid, the world’s largest heart conference.
The study’s lead author, Ghita Housni, of the William Harvey research institute at Queen Mary University of London, said: “We know cleaner air means healthier hearts, and this research lays bare the impact of air pollution on public health.
“Reducing your exposure to air pollution is a crucial part of preventing heart conditions in the modern age and lowering your risk of heart failure and stroke. We need to improve air quality by introducing public health strategies which strongly prioritise cardiovascular protection.”
In the study, researchers tracked 299,323 people for a decade between 2010 and 2020.
Using data from the UK Biobank study, the team looked at average levels of PM2.5 in the areas where the participants lived. They then investigated rates of heart failure and stroke in the same people over a decade.
PM2.5 is a pollutant released from sources including vehicles, industry and household heating. The particles are 30 times smaller than the width of a human hair, making them small enough to get into the bloodstream after being inhaled.
Those living in the worst 10% of areas for PM2.5 pollution had a 27% higher risk of developing heart failure, compared with people in the least worst 10% of areas for PM2.5 pollution. The risk of having a stroke was 7% higher for people in the areas with the dirtiest air, the study found.
For every extra one microgram in an area where people lived, the risk of developing heart failure increased by 7% and the stroke risk grew by 3%.
There was also a slight increase in the risk of someone experiencing a heart attack with more PM2.5, but the link was not statistically significant.
Because PM2.5 does not belong in the body, when it is breathed in, the immune system overreacts to cause inflammation. When blood vessels become inflamed, they become stiffer and more prone to fatty build-up.
This can lead to high blood pressure, which increases the risk of having a stroke. The heart also has to work harder to pump blood through inflamed blood vessels, which over time can make it become weaker, and develop heart failure.
The findings are significant because the increase in stroke and heart failure risks seen with higher PM2.5 levels were recorded after researchers adjusted for a range of factors, including age, sex, ethnicity, residential setting (urban or rural), deprivation, education, smoking status and alcohol consumption.
Researchers found one extra person in every 100 experienced a stroke in the top 10% of polluted areas, compared with the areas with the cleanest air. Another two people in every 100 developed heart failure in the areas with the dirtiest air.
The team analysed data without looking at specific places, so the results did not reveal which locations in the UK may raise the risk of residents developing heart failure or having a stroke.
The UK’s air pollution has dropped in the last decade, but scientists say dangerous levels continue to be reached.
Despite a 30% reduction in PM2.5 since 2015, safety limits are still broken in the UK. There are still 22 days a year on average when PM2.5 levels exceeded World Health Organization targets.
Dr Sonya Babu-Narayan, clinical director at the British Heart Foundation, said: “We know there are no safe levels of air pollution. These early findings linking high PM2.5 levels to heart failure add to a growing body of evidence that poor air quality is damaging to our hearts.
“It’s good to know that the kind of PM2.5 levels experienced by the people in this study have already improved since the introduction of government targets in 2021. Nevertheless, these levels still exceed World Health Organization guidelines.
“Going further to reduce air pollution could help the UK to prevent premature cardiovascular disease, and save and improve lives for current and future generations.”