Even low air pollution levels can alter heart structure

People exposed to even low levels of air pollution have changes in the structure of the heart, similar to those seen in the early stages of heart failure, a study has found.

The researchers from Queen Mary University of London in the UK 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 study, published in the journal Circulation, found a clear association between those who lived near loud, busy roads, and were exposed to nitrogen dioxide (NO2) or PM2.5 - small particles of air pollution -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. For every one extra microgramme per cubic metre of PM2.5 and for every 10 extra microgrammes per cubic metre of NO2, the heart enlarges by about one per cent.

In the study, average annual exposures to PM2.5 were well within UK guidelines (25 microgrammes per cubic metre), although they were approaching or past World Health Organisation (WHO) guidelines (10 microgrammes per cubic metre).

"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 Nay Aung, who led the data analysis from Queen Mary.

"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," Aung said.

"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," he said.