Are Low Pollution Levels Safe?

A study conducted by Queen Mary University in London has found a correlation between prolonged exposure to low level pollution and modifications in the structure of the heart. Although the research did not find causal links to heart complications, the restructuring evidenced by its subjects is often seen in the first stages of heart failure.

This has led those behind the study to speculate that concentrations of nitrogen dioxide (NO2) and particulate matter 2.5 (PM2.5) which were previously considered as safe may pose a long-term risk to human health. The findings are in agreement with a similar study carried out in Belgian in 2015, which also concluded that “safe” pollution levels could precipitate heart attacks.

Worrying results

Lead author on the study was Professor Steffen Petersen, who published his findings in the journal Circulation. Petersen and his team collated data from 3,920 volunteers between the ages of 55 and 69 who submitted information about their home and work addresses, lifestyles and health histories. They were also subjected to blood and health tests and heart MRI scans were used to measure the size, shape, weight and performance of their hearts.

The results showed that those participants living on or near busy roads were exposed to higher concentrations of NO2 and PM2.5 and as a result, the restructuring of ventricles in their heart. Indeed, there was a direct correlation between increased exposure to pollution and a largening of the ventricles, with every 1µg/m³ increase in PM2.5 and every 10µg/m³ in NO2 leading to a 1% increase in the size of the ventricles.

The enlargement of these ventricles is not necessarily a concerning sign on its own and none of the subjects showed any deterioration in their heart’s function, but the finding has been flagged as a warning sign by the researchers because it is commonly observed in the early stages of heart failure.

Public beware

The study is most concerning because the levels of pollution to which the subjects were exposed were well under the threshold which the UK government deems to be safe. This means that far more people may be at risk of developing heart complications in later life than previously thought.

The study was partly funded by the British Heart Foundation and their associate medical director Professor Jeremy Pearson said that its findings were a clear indication that the government must do more to improve air quality and reduce transport-related pollution. “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,” he commented.

“What is particularly worrying is that the levels of air pollution, particularly PM2.5, 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.”