People exposed to levels of air pollution that fall "well-within guidelines" for Britain can suffer damage to their hearts, scientists reported on Friday.

A team of researchers led by scientists at Queen Mary University of London found that, after adjusting for confounding variables, many people with low-level pollution exposure showed changes in heart structure "similar to those seen in the early stages of heart failure."

The study, published in the medical journal Circulation, examined data from some 4,000 volunteers in a British health project, using blood tests, health scans and magnetic resonance imaging to measure heart function.

The researchers noted that air pollution is the largest environmental risk factor linked to deaths in Britain.

"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," said Dr Nay Aung of Queen Mary's, who led the data analysis.

In its new "clean air strategy," the British government has proposed halving the number of people living in areas where levels of PM2.5 - suspended particles smaller than 2.5 micrometers - exceed WHO guidelines of 10 micrograms per cubic meter.

Jeremy Pearson, associate medical director of the British Heart Foundation, said the study showed that government needed to adopt the WHO guidelines as soon as possible.

"We can't expect people to move home to avoid air pollution," Pearson said. "Government and public bodies must be acting right now to make all areas safe and protect the population from these harms."