Even low levels of air pollution linked with serious changes in the heart, according to new UK research

The study, led by Professor Steffen Petersen, was part-funded by the British Heart Foundation (BHF) and published in the journal Circulation.

It 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.

Pollution levels within UK guidelines

The team found a clear association between those who lived near loud, busy roads, and were exposed to nitrogen dioxide (NO₂) or PM_2.5 -- 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 1 extra µg per cubic metre of PM_2.5 and for every 10 extra µg per cubic metre of NO₂, the heart enlarges by approximately 1 per cent.

In the study, average annual exposures to PM_2.5 were well within UK guidelines (25µg per cubic metre), although they were approaching or past World Health Organisation (WHO) guidelines (10µg per cubic metre).

'Doctors and the general public all need to be aware'

Air pollution is now the largest environmental risk factor linked to deaths in England. The UK Government's consultation on their draft Clean Air Strategy closes on 14 August 2018, which commits to halving the number of people in the UK living in areas where PM_2.5 levels exceed WHO guidelines (10µg per cubic metre) by 2025. Following this research, the BHF are calling for this action to go further to reduce the health impacts of toxic air as quickly as possible.

Dr Nay Aung who led the data analysis from Queen Mary's William Harvey Research Institute and Barts Health NHS Trust 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.

"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."

Professor Jeremy Pearson, Associate Medical Director at the BHF said: "We can't expect people to move home to avoid air pollution -- 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 PM_2.5, at which this study saw people with heart remodelling are not even deemed particularly high by the UK Government -- this is why we are calling for the WHO guidelines to be adopted."

This research was a collaboration between Queen Mary University of London, Barts Heart Centre and the University of Oxford.