Air Pollution, Asthma, and Heart Health

Research published in the European Heart Journal on March 12, 2019, made a shocking statement: air pollution now kills more people than smoking.

Considerations for the dangers of air pollution

When I heard this fact offhandedly mentioned in a podcast last week, considerations for why began tumbling through my head: Is it because climate change is amplifying the effects of air pollution? Is it because we are having a lower mortality rate from smoking overall, shifting the balance between these two killers? Is it because of the rising incidence of heart and lung diseases—including asthma? Is it because of the rising incidence of overall heart and lung diseases in tandem with the rise in air pollution and the effects of climate change? Is it because we’ve become better at dissuading people from smoking, and/or treating smoking-related diseases?

Finally, on March 19th, I went to see if I had access to the journal—by a miracle of academic publishing and institutional access, I did! While these questions above weren’t answered (I guess both the researchers and I need to get digging for more facts!), I was able to make some connections between this research and how it could impact those of us with asthma. And, beyond that, as those of us with asthma are likely more invested in clean air, and can share research on air quality and health with others.

Background on pollution, asthma, and heart health

A preamble, before we get to the research. Being that it was a European Heart Journal (EHJ) published study, the paper’s title was, "Cardiovascular disease burden from ambient air pollution in Europe reassessed using novel hazard ratio functions". Do I have any idea what that means? No, of course not.

Most simply, it appears that a hazard ratio is “a measure of an effect of an intervention on an outcome of interest over time”.¹ According to ScienceDirect, a hazard ratio compares the risk to those exposed to a situation or intervention to those not exposed—“a hazard ratio of 1 means lack of association”, therefore, no correlation between exposure and risk ². A hazard ratio of less than 1 suggests a smaller risk of hazard, and a hazard ratio score of greater than 1 means greater risk.²

While the study did not specifically mention asthma, nor provide specific disease categories that could have included asthma,³ it did cite that environmental risks, such as air pollution, “pose additional risks with health implications that have been underestimated in the Global Burden of Disease […]”^3,4

The environment affects our physical health

Environmental effects of air pollutants and “fine" particulate matter, such as fossil fuels, combustion, industrial and agricultural products/byproducts, and “wind-blown dust”³, and these certainly impact asthma morbidity (effects of a disease or rate of disease incidence). This same type of particulate matter, PM2.5, is also what makes smoke so hazardous—read more about PM2.5 here.

Research documents that changes of disease incidence⁵, including with regard to asthma and allergies⁶, are occurring due to climate change—and that air pollution and climate change are linked—quite possibly inextricably so.⁷

While modern medications may so far be helping most of us avoid major effects of climate change on our asthma, the US Global Change Research Program projects a worsening of asthma in a 2014 graphic, in part due to increased atmospheric ozone, causing increased symptoms⁸, and an increased incidence of asthma in the 2018 report.⁹ I wrote in another post that those diagnosed with asthma in adulthood may be at higher risk of cardiovascular disease, which means these results could also have an even greater impact on asthmatics than meets the eye.

As such, beyond what may seem obvious impacts of poor air quality on asthma, it seems reasonable that we can infer at least some of the research from the March 2019 heart study to be applicable to asthma.

What this research found about air pollution and asthma

The World Health Organization, as cited in the EHJ study, estimates 7.2 million people per year die as a result of cigarette smoking.³ The authors of the EHJ study estimate that in 2015, 8.9 people per year die as a result of diseases linked to air pollution—including heart and vascular diseases, specific cancers, lower respiratory infections/illnesses.³ The study identified there to be much higher quantities of PM2.5—air pollutants—than did data gathered just three years ago in 2015.³

To counteract the increase in deaths which could be linked to air pollution, the researchers “conclude that improving European air quality is an achievable, highly effective, and therefore imperative health promotion intervention”.³ This certainly applies to the rest of the world as well. The authors recommend replacing fossil fuel sources with clean, renewable fuels.³

While these changes are also needed to meet the goals of the Paris Climate Agreement, the authors also acknowledge that meeting the targets set out in the Agreement could reduce the air pollution linked mortality rate in Europe by 55%.³ This is huge, even without adding that they do believe additional changes to industry and agriculture could have an even more profound effect.

How this research links air pollution and asthma

While we cannot yet say that air pollution causes asthma, a study cited in The Guardian (article published July 2018) states that asthma deaths have increased 25% over the course of a decade in England and Wales (an area that would have, at the time, been captured in the EHJ study), as air pollution has been worsening worldwide.⁸

Future research, I hope, will give us more detailed information on actions we as individuals can take to not only help improve our environment and air quality but also to understand better how we can protect our already hyper-sensitive lungs from the impacts of climate change and poor air quality exposure.