Researchers have found that people exposed to air pollution levels well within UK guidelines have changes in the structure of the heart, similar to those seen in the early stages of heart failure.
The research was part-funded by the British Heart Foundation and is published in the journal, Circulation.
A team of scientists, led from Queen Mary University of London by Professor Steffen Petersen, studied data from around 4,000 participants in the UK Biobank study.
Volunteers provided a range of personal information, including their lifestyles, health record, and details on where they have lived, so that the research team were able to remove patients with underlying heart problems, or those who had moved house during the study.
Participants also had blood tests and health scans. Heart MRI (magnetic resonance imaging) was used to measure the size, weight, and function of the participants’ hearts at fixed times.
Even though most participants lived outside major UK cities, there was 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 µg per cubic metre of PM2.5 and for every 10 extra µg per cubic metre of NO2, the heart enlarges by approximately one per cent.
Globally, coronary heart disease and stroke account for approximately six-in-10 (58 per cent) deaths related to outdoor air pollution. This research could help explain exactly how and why air pollution affects the heart.
In the study, average annual exposures to PM2.5 (8-12µg per cubic metre) were well within UK guidelines (25µg per cubic metre), although they were approaching or past World Health Organisation (WHO) guidelines (10µg per cubic metre). The WHO has said that there are no safe limits of PM2.5. The participants’ average exposure to NO2 (10-50µg per cubic metre) was approaching and above the equal WHO and UK annual average guidelines (40µg per cubic metre).