July 31, 2023

expert reaction to study looking at air pollution exposure and atrial fibrillation risk

A study published in PNAS looks at air pollution, genetic susceptibility, and the risk of atrial fibrillation.

Dr Richard Francis, Head of Research, the Stroke Association, said:

“Atrial fibrillation (AF) is a type of irregular heart rhythm that makes it five times more likely that you’ll have a stroke.  AF-related strokes are also more deadly and disabling.  This is the first study to comprehensively look at the links between genetic risk of AF and air pollution.

“This study indicates that long-term exposure to air pollution is linked to increased risk of AF, especially in people who are already at an increased genetic risk of AF.  As the authors note, we need to be cautious about how we interpret this finding given that UK Biobank volunteers are a healthy and largely white population, and it’s known that AF risk varies with ethnicity and with certain health conditions like diabetes.  The true relationship between AF, air pollution, genetics and other risk factors is likely to be extremely complex.

“However, it’s already clear that air pollution is a risk factor for many health conditions including stroke, asthma, diabetes, lung cancer, heart disease and dementia.  We urge the government to commit to improving air quality to the standards set by the WHO and outline appropriate strategies that can reduce air pollution, so people are protected from its damaging effects to their health, no matter what future research reveals about its role in AF risk.  The government has a role to play in improving public awareness of air pollution, so that people can manage their own exposure.

“Improving air quality has the potential not only to help those at risk of AF and stroke but the whole population.  This will help to save lives, improve public health and result in substantial cost-savings for the NHS.”

Prof Anna Hansell, Professor of Environmental Epidemiology; Director of the Centre for Environmental Health and Sustainability; and Director of the NIHR Health Protection Research Unit in Environmental Exposures and Health, University of Leicester, said:

“Investigation of interactions between combinations of genetic factors and air pollution is important to identify those who may be most susceptible to ill effects of air pollution.  However, given some issues with the way in which air pollution exposure has been estimated in this paper, it is difficult to have confidence in the estimated size of the effects.  Given known associations of long-term air pollution with heart disease including atrial fibrillation – even at lower concentrations – reduction of air pollution levels is important to improve public health.  However, more studies are needed before considering targeted medical care for individuals with a particular genetic make-up, in relation to air pollution exposures.

“Detailed comments on air pollution exposure estimates: Unfortunately, and in common with some other recent studies, the researchers have incorrectly averaged estimates of two different air pollution models in UK Biobank used to estimate exposures at enrolment in the study (the ESCAPE model for 2010 and a European model for 2005-7).  This may introduce bias as these models are different and were not designed to be combined.  Results affected are for PM10 and NO2 air pollutant analyses (which are the two pollutants where additive interactions between the air pollutant and the genetic risk score were identified).  In supplementary analyses, the authors added in a further two different types of exposure models at 1mk and 3km grids to look at impacts of cumulative exposure and short-term exposure respectively.  They didn’t find effects in these supplementary analyses, but the spatial scale may have resulted in making it more difficult to detect effects due to errors in estimating exposure especially for NO2 pollution, which is much higher along roads (therefore the actual exposures may be diluted if using a 1km average).  Issues with exposure models and potential impact on results were not discussed in the paper.  While interactions between air pollution and genetic factors is certainly plausible, further studies exploring these are needed.”

‘Air pollution, genetic susceptibility, and the risk of atrial fibrillation: A large prospective cohort study’ by Yudiyang Ma et al. was published in PNAS at 20:00 UK time on Monday 31 July 2023.

DOI: 10.1073/pnas.2302708120

Declared interests

Dr Richard Francis: “No COIs to declare.”

Prof Anna Hansell: “I do not have conflicts of interest to report. I am Chair of the Committee on the Medical Effects of Air Pollution (COMEAP), but comments here are in a personal capacity as Professor of Environmental Epidemiology at the University of Leicester.”