Yale researchers say just a few hours spent breathing polluted air may cause a heart attack

Air pollution is an often overlooked problem in the US. While it’s true that smog in U.S. cities isn’t nearly as bad as in other areas of the world, such as India or China, air pollution is quite literally all around us. If you live in any type of major metropolitan area, chances are you breathe in polluted air each and every day. 

But, how bad could a little bit of smog really be? Well, according to a recent piece of Yale research, just a few hours of exposure to ambient ultrafine particles (UFP) may trigger a nonfatal heart attack. It’s important to make the distinction between a fatal and nonfatal heart attack, but at the end of the day, any type of heart attack is a major health emergency.

This study was a joint effort that included a number of German collaborators, including the Helmholtz Center Munich, Augsburg University Hospital, and Nördlingen Hospital.

You may be wondering exactly what is meant by ambient ultrafine particles. These super tiny air particles are only 100 nanometers or smaller in size and are primarily deposited into the air via car emissions. It’s perhaps this aspect of the study that’s most unsettling. Aside from people living in more rural areas of the country, we are all in close proximity to cars and their exhausts every single day.

Suddenly a 2018 World Health Organization report that concluded nine out of 10 people on a global scale breathe polluted air each day doesn’t sound so far fetched. That same report estimated that seven million people die each year due to smog. 

There have been a number of studies performed on the harmful effects of smog on public health, and besides just physical repercussions, polluted air exposure has been linked to depression, anxiety, and an increased risk of developing dementia. 

However, this study is considered the first ever to comprehensively analyze the effects of just UFP (there are various types of other air pollutants such as PM10 and PM2.5) on heart attack risk while also considering time spent exposed, particle length, number of particles, and surface area concentrations.

“This study confirms something that has long been suspected–air pollution’s tiny particles can play a role in serious heart disease. This is particularly true within the first few hours of exposure,” explains first study author Kai Chen, Ph.D., an assistant professor at Yale School of Public Health, in a press release. “Elevated levels of UFP are a serious public health concern.”

Ultrafine particles are especially dangerous to breathe in because they are small enough to enter our cells and penetrate the bloodstream, but just big enough to do some serious damage as well.

“We were the first to demonstrate the effects of UFP on the health of asthmatics in an epidemiological study in the 1990s,” says co-author Annette Peters, director of the Institute of Epidemiology at Helmholtz Center Munich. “Since then approximately 200 additional studies have been published. However, epidemiological evidence remains inconsistent and insufficient to infer a causal relationship.”

Chen and his team analyzed data on 5,898 nonfatal heart attack patients in Augsburg, Germany between the years 2005 and 2015. For each heart attack, the study’s authors looked into the UFP air pollution readings for the exact hour and location where the patient suffered his or her cardiac event. They also accounted for any additional contributing factors, such as the individual’s socioeconomic status and the day of the week in which the heart attack occurred.

“This represents an important step toward understanding the appropriate indicator of ultrafine particle exposure in determining the short-term health effects, as the effects of particle length and surface concentrations were stronger than the ones of particle number concentration and remained similar after adjustment for other air pollutants,” Chen concludes. “Our future analyses will examine the combined hourly exposures to both air pollution and extreme temperature. We will also identify vulnerable subpopulations regarding pre-existing diseases and medication intake.”

There’s a whole lot to love about city living. From Manhattan to smaller cities like Nashville or New Orleans, America’s cities offer something for everyone. Culture, great restaurants, and nightlife, just to name a few benefits. This study perhaps represents the darker side of urban life, in which we’re all constantly surrounded by cars and at least a certain degree of air pollution. 

The idea of a city with no cars probably sounds preposterous to most Americans, but a number of European cities are already making great strides in eliminating car traffic. Both Oslo in Norway and Madrid, Spain have banned cars from their city centers in recent years, and the Belgian city of Ghent has been completely car-free since 2017. As we continue to learn more about the detrimental health effects of air pollution, it may soon be time for U.S. cities to consider similar changes.

The full study can be found here, published in Environmental Health Perspectives.