Researchers have found that people exposed to even low levels of air pollution can have changes in the structure of the heart, similar to those seen in the early stages of heart failure.

For every one extra microgram per cubic metre of PM2.5 — small particles of air pollution — and for every 10 extra microgram per cubic metre of nitrogen dioxide (NO2), the heart enlarges by approximately 1 per cent, showed the findings of the Britain-based study published in the journal Circulation.

“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 one of the researchers Nay Aung from Queen Mary University of London.

For the study, the researchers looked at data from around 4,000 participants in the UK Biobank study, where volunteers provided a range of personal information, including their lifestyles, health record and details on where they have lived.

Participants also had blood tests and health scans, and heart MRI (magnetic resonance imaging) was used to measure the size, weight and function of the participants’ hearts at fixed times.

The team found a clear association between those who lived near loud, busy roads, and were exposed to nitrogen dioxide or PM2.5 and the development of larger right and left ventricles in the heart.

The ventricles are important pumping chambers in the heart and, although these participants were healthy and had no symptoms, similar heart remodelling is seen in the early stages of heart failure.

Higher exposures to the pollutants were linked to more significant changes in the structure of the heart, the findings showed.