The Heart of the Matter: Air Pollution’s Cardiovascular Toll

A woman running in the city, running improves cardiovascular health, however poor air quality indoors and outdoors has been linked to poor cardiovascular health.

We’ve spoken about the effects of air pollution many times before, but it's time to get to the “heart” of the matter. ActivePure summarizes 3 recent studies exploring environmental cardiology — that is — how air quality affects your heart’s health.

Outdoor Air Pollution & Arrhythmias

Per the Mayo Clinic, an arrhythmia is an irregular heartbeat caused “when the electrical signals that tell the heart to beat don't work properly.” Some are of minimal concern, while others can be deadly. A study by scientists at Fudan University in China published a 2023 paper in the Canadian Medical Association Journal exploring the connection between symptomatic arrhythmias and air pollution exposure. By comparing records of almost 200,000 patients admitted to Chest Pain Centers with data from the nearest air quality monitoring stations, they found that many pollutants can cause the onset of arrhythmia within hours.

A type of arrhythmia called an atrial flutter appears to be most affected by air pollution. As the Mayo Clinic explains, atrial flutters can “increase the risk of stroke, heart failure[,] and other complications.” Of the 6 criteria air pollutants, nitrogen dioxide (NO2) seemed to be the biggest troublemaker, while ozone (O3) was the least problematic (for that trigger). Particulate matter (both PM2.5 and PM10), sulfur dioxide (SO2), and carbon monoxide (CO) fell somewhere in between.

After 24 hours of exposure, the risk of arrhythmia drops for every pollutant except PM2.5. This is good news, as it suggests that the effects of air pollution (at least as it pertains to heart rhythms) don’t persist. However, it’s also bad news, as it means that even short-term exposure can have a noticeable health effect. Oddly, this short-term effect was most noticeable “in patients under 65 years.”

Why do arrhythmias occur due to air pollution? We’re not certain. However, one theory is that the inflammation caused by contaminants can impact the functioning of the autonomic nervous system — that is — stuff in your body swells, and thus your brain can’t send signals as easily to your heart.

Most pertinently, the study found that “[the] curves depicting the exposure-response relationship between all air pollutants and arrhythmia onset increased monotonically and were, in general, approximately linear, without any apparent concentration thresholds.” In other words, there’s no point at which the amount of exposure goes from safe to dangerous. Air pollution is undesirable at any amount.

Outdoor Air Pollution & Cardiac Hospital Admissions

Scientists at Harvard’s T.H. Chan School of Public Health published a 2024 paper in The BMJ exploring the relationship between particulate matter and hospital admission due to cardiovascular disease. By comparing the hospital records of nearly 60 million Medicare patients with estimated PM2.5 levels in their zip codes, the scientists discovered that “[3-year] average PM2.5 exposure was associated with increased relative risks of first hospital admissions for ischemic heart disease, cerebrovascular disease, heart failure, cardiomyopathy, arrhythmia, and thoracic and abdominal aortic aneurysms.” That sounds very concerning.

You’ll notice this is a “relative risk;” relative to what? The USC team wanted to contrast hospital admissions at the WHO’s recommended PM2.5 exposure limit (≤5 µg/m3) to the EPA’s new limit (9 μg/m3). (If you are curious, in the US PM2.5 averages 9.7 μg/m3). The study concluded that the new EPA standard is “not sufficient for the protection of public health.” In fact, they predict a 15% difference in hospital admissions between the 2 standards.

Unlike the arrhythmia study above, the Harvard paper found that the effects of PM exposure linger for up to 3 years. Like the arrhythmia study, they didn’t find a magic point at which the pollution went from safe to dangerous. As the paper’s abstract states:

“The findings of this study suggest that no safe threshold exists for the chronic effect of PM2.5 on overall cardiovascular health.”

Indoor Air Pollution & Cardiac Mortality

Scientists at the University of Southern California’s Keck School of Medicine studied the household fuel use of 50,000 individuals in Iran between 2004 and 2008. They found that 10 years of kerosene and/or diesel fuel use led to approximately a 17-point increase in cardiovascular mortality compared with the “cleaner” fuel of natural gas.

The USC study theorizes that this cardiac mortality increase is due to “inhaled toxicants stimulating systemic inflammation, oxidative stress, and the autonomic nervous system, leading to increased leukocyte epigenetic changes, coagulation, thrombosis, and vasoconstriction.” In other words, fuel exhaust stresses and inflames your body, which reduces blood flow and messes up your immune/nervous systems.

Half of the world still uses such risky fuels for their cooking, lighting, and heating needs; “the resultant household air pollution (HAP) is the third largest risk factor for global disease burden, contributing to an estimated 3.5 million deaths in 2010.”

If you are not a member of this half of the population, you may be wondering why any of this is relevant to you. There are 3 reasons:

  1. It viscerally illustrates why you should save that fireplace for special occasions, and heat your home with something a bit more targeted; health-wise, burning wood appears to be on par with dried animal dung.
  2. Members of your own family are likely exposed to diesel exhaust daily, especially during their ride on the city school bus.
  3. It’s important to understand the difference between relative and absolute risk. Relative to the impoverished half of the world, natural gas might be pretty decent. However, decent just isn’t good enough. In addition to the production of PM, CO, CO2, and NO2, gas stoves have been linked with the development of asthma in children.

A Heartfelt Opportunity

If you take one thing away from these 3 studies, it should be that there is no “safe” threshold for many air pollutants. Such a revelation should not lead to panic; instead, it's an opportunity. Any reduction of indoor contaminants is likely to reduce your risk that much more; and there are many ways to reduce contaminants — from improved ventilation to air purification to real-time monitoring.

ActivePure helps homes, hospitals, schools, and businesses find the air quality solution that works best for their budget and building. Get to the heart of the matter — contact us to start improving your indoor air quality today.

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