Structural Cardiac Changes Associated with Low-Level Air Pollution Exposure

A new British study has found that even low levels of air pollution can cause serious structural changes to occur in the heart.[i]

Of the 3,920 participants recruited, none had heart disease when the study began. Measuring exposure to ambient air pollutants, researchers estimated figures using Land Use Regression models (developed by the ESCAPE project, a European project designed to estimate air pollution due to particular air contaminants) for the participants’ home addresses, between 2005 and 2010. The participants’ hearts were studied using magnetic resonance imaging (MRI). 

The researchers found that both particulate matter, with diameter of less than 2.5 mm (PM2.5), and nitrogen dioxide were associated with changes in the left and right ventricles of the heart.  PM2.5 and nitrogen dioxide are both emitted by diesel engines.

Further, there was a clear association between living near busy roads and the development of larger ventricles. 

The right and left ventricles are chambers of the heart responsible for pumping de-oxygenated blood to the lungs and oxygenated blood to the rest of the body, respectively. Ventricles can be enlarged by high blood pressure, which causes the heart to have to work harder.  As a result, having enlarged ventricles is seen as a precursor to heart disease.

Figure: Fairview[ii]

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The researchers also found that increased exposure to pollutants was associated with more significant changes to the structure of the heart.  For every additional 10 micrograms of PM2.5 per cubic metre of air and for every additional 10 parts per billion of nitrogen dioxide, the heart enlarged by 1.28% and 1.7%, respectively. 

However, there was no association between larger airborne particles and heart structure.

It is worth noting that concentrations of PM2.5 exposure fell well within the UK guidelines, stipulating 25 micrograms per cubic metre, and were closer to the World Health Organisation guidelines of 10 micrograms per cubic metre.  The median concentration of PM2.5 to which participants were exposed was 9.9 micrograms per cubic metre.

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, stated:

‘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 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’.[iii]

Exposure to diesel exhaust fumes is associated with a range of health effects, including:

  • lung cancer;
  • bladder cancer;
  • other cancers;
  • asthma and respiratory disorders;
  • reproductive disorders; and
  • amyotrophic lateral sclerosis.

This latest study, despite not demonstrating a causal relationship, offers some evidence that diesel exhaust exposure may also have detrimental effects on heart health. Even though this study considered residential exposure to air pollution, the results may also be consistent with exposed workers in agriculture, mining, large haulage and transport vehicle industries.

 

 

[i] N. Aung, et al. Association Between Ambient Air Pollution and Cardiac Morpho-Functional Phenotypes: Insights From the UK Biobank Population Imaging Study. Circulation, 2018; DOI: https://doi.org/10.1161/CIRCULATIONAHA.118.034856 (Accessed 7 August 2018)

[ii] ‘When Your Child Has a Hypoplastic Right Ventricle: Tricuspid Atresia’ (Fairview) <https://www.fairview.org/patient-education/89171> accessed 7 August 2018.

[iii] Even low levels of air pollution linked with serious changes in the heart, according to new UK research. ScienceDaily, 3 August 2018.  https://www.sciencedaily.com/releases/2018/08/180803103315.htm (Accessed 7 August 2018).