Millions more people than previously thought are at risk of heart problems caused by air pollution, a study suggests.
Anyone living near a busy road – even those outside major cities – could be gravely affected by traffic fumes, the researchers found.
Even supposedly safe emission levels can have a significant impact on the shape and size of the heart, they discovered.
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The research team from Queen Mary University of London and the University of Oxford scanned the hearts of 4,000 people and compared the data to where people lived.
They also monitored levels of the microscopic sooty particles emitted by diesel cars, known as PM2.5.
They found the higher someone’s exposure to PM2.5 fumes, the more likely they were to have enlarged heart chambers.
Crucially, the team found that even at a pollution level below ten micrograms per cubic metre – significantly below the ‘legal’ limit of 25 at which people are thought to be safe – patients were showing signs of heart damage.
The participants, who all lived within 25 miles of Stockport in north-west England, had an average exposure level of 9.9mcg.
Although some participants lived in Manchester – a major city with bad pollution – the majority lived closer to Stockport, including in rural parts of the Peak District National Park.
Despite this, the average person scanned showed signs of pollution damage which could eventually lead to major problems. If the heart’s chambers become too big, it loses pressure and power, meaning it cannot pump as much blood around the body.
This puts people at greater risk of heart attack, heart failure or death.
The researchers, who publish their findings in the Circulation medical journal today, found for every 1mcg increase in levels of PM2.5 particles – the heart enlarged by 1 per cent.
Dr Nay Aung, who led the data analysis, said: ‘Although our study was observational and hasn’t yet shown a causal link, we saw significant changes in the heart, even at relatively low levels of air pollution exposure.
‘Our future studies will include data from those living in inner cities like central Manchester and London, using more in-depth measurements of heart function, and we would expect the findings to be even more pronounced and clinically important.
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‘Air pollution should be seen as a modifiable risk factor. Doctors and the general public all need to be aware of their exposure when they think about their heart health, just like they think about their blood pressure, their cholesterol and their weight.’
The team found one of the risks was how close someone lived to a ‘major’ road – defined as carrying at least 5,000 cars a day, the equivalent of an average A road.
The closer people lived to such a road, the higher their risk of pollution exposure and heart damage.
The UK is notoriously bad at controlling air pollution, with 37 cities persistently displaying ‘illegal’ levels.
Yet the new research suggests even people who live outside these areas, with relatively clean air, are at risk.
Professor Jeremy Pearson of the British Heart Foundation, which part-funded the study, said: ‘We can’t expect people to move home to avoid air pollution – the Government and public bodies must be acting right now to make all areas safe and protect the population from these harms.
‘What is particularly worrying is that the levels of air pollution, particularly PM2.5, at which this study saw people with heart remodelling are not even deemed particularly high by the UK Government.
‘They are less than half of UK legal limits.’
More than 40,000 people are thought to die early every year in the UK because of air pollution.