Researchers are now looking at exactly how living in an air polluted area can cause changes in the heart, even when the pollution is within the government-approved range.
Researchers from Queen Mary University of London have found that exposure to air pollution levels that are within the U.K. guidelines can still cause structural changes in the heart, similar to what is seen in the early stages of heart failure.
“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,” Nay Aung, PhD, who led the data analysis from Queen Mary University of London, said in a statement. “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,” he added. “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.”
The researchers examined the data from about 4,000 participants in the UK Biobank study, where volunteered submitted personal information that included their lifestyles, health records and details of where they have lived. This enabled the team to remove patients with underlying heart problems or those who moved during the course of the study.
The participants in the study were also administered blood tests, health scans, and MRIs to measure the size, weight and function of the participants’ hearts at fixed times.
While the majority of the volunteers lived outside of major cities, the researchers found a clear association between those who lived near heavy trafficked roads and exposure to nitrogen dioxide or PM2.5—small particles of air pollution—and the development of larger right and left ventricles in the heart.
However, the participants were ultimately deemed healthy with no symptoms, similar to how heart remodeling is seen in the early stages of heart failure.
More significant changes in the heart were linked to higher levels of exposure to the pollutants. For every one extra μg per cubic meter of PM₂.₅ and for every 10 extra μg per cubic meter of NO₂, the heart enlarges by approximately 1 percent.
The average annual exposures for participants in the study to PM₂.₅ was eight to 12 μg per cubic meter, which are well within the U.K. guidelines of 25 μg per cubic meter. The World Health Organization (WHO) has previously said there is no safe limits of PM₂.₅.
Study participants also had an average exposure to NO₂ was 10 to 50 μg per cubic meter, which is approaching or above the equal WHO and U.K. annual average guidelines of 40 μg per cubic meter.
According to the study, coronary heart disease and stroke account for about 58 percent of the deaths related to outdoor air pollution.
“We can’t expect people to move home to avoid air pollution—governments and public bodies must be acting right now to make all areas safe and protect the population from these harms,” professor Jeremy Pearson, associate medical director at the British Heart Foundation, which part-funded the study, said in a statement. “What is particularly worrying is that the levels of air pollution, particularly PM₂.₅, at which this study saw people with heart remodeling are not even deemed particularly high by the UK government—this is why we are calling for the WHO guidelines to be adopted.
“They are less than half of UK legal limits and while we know there are no safe limits for some forms of air pollution, we believe this is a crucial step in protecting the nation’s heart health,” he added. “Having these targets in law will also help to improve the lives of those currently living with heart and circulatory diseases, as we know they are particularly affected by air pollution.”