Air pollution can induce a heart attack within an hour.

A recent Chinese study discovered that the risks were higher among the elderly and when the weather was cooler.

The study discovered that any combination of four common air contaminants could cause the start of acute coronary syndrome. The term “ACS” refers to any circumstance in which blood supply to the heart muscle is obstructed, such as in a heart attack or unstable angina, which is chest discomfort produced by blood clots that temporarily block an artery. The greatest danger occurred within the first hour of exposure and gradually decreased over the day.

The harmful effects of air pollution on the cardiovascular system have been widely recognized. But we were nevertheless taken aback by the speed with which the impacts manifested “Haidong Kan, a professor at Fudan University’s School of Public Health in Shanghai, agreed. He led the study, which was published in the American Heart Association journal Circulation on Friday.

“Another surprise was the non-threshold effects of air pollution. In other words, any concentrations of air pollutants (such as fine particulate matter, nitrogen dioxide, sulfur dioxide and  carbon monoxide recorded in the present study may have the potential to trigger the onset of a heart attack.” 

Haidong Kan, a professor in the School of Public Health at Fudan University in Shanghai

Another unexpected finding was the non-threshold consequences of air pollution, he stated. In other words, all amounts of air pollutants (such as fine particulate matter, nitrogen dioxide, sulfur dioxide, and carbon monoxide) measured in the current study may have the potential to cause a heart attack.

Fine particulate matter—microscopic solids or liquid droplets emitted by automobiles, power plants, construction sites, and other pollution sources—has been indisputably linked to heart disease, stroke, and other health problems, as well as 4.2 million premature deaths globally. These particles can be so minute that they can enter the lungs or even the bloodstream if breathed in.

Researchers examined medical records for roughly 1.3 million people treated for heart attacks and unstable angina at 2,239 hospitals in 318 Chinese cities between 2015 and 2020 for the new study. They compared the hourly onset timings of cardiac events to levels of fine and coarse particulate matter, nitrogen dioxide, sulfur dioxide, carbon monoxide, and ozone.

The development of all kinds of acute coronary syndrome has been linked to short-term exposure to any quantity of fine particulate matter, nitrogen dioxide, sulfur dioxide, and carbon monoxide.

As the levels of the pollutants analyzed increased, so did the chance of heart attack. Exposure to nitrogen dioxide was the most significantly associated, followed by fine particulate matter, and was most harmful in the first hour after exposure. The association was strongest in people 65 and older with no history of smoking or other respiratory disorders, as well as in those exposed during the colder months.

“The cardiovascular impacts of air pollution should be a major concern for everyone, including politicians, clinicians, and individuals,” Kan added. “Our findings highlight the importance of strengthening air quality regulations, stricter air pollution control, and timely public health response for policymakers.”

According to Dr. Sanjay Rajagopalan, head of the Cardiovascular Research Institute at Case Western Reserve University in Cleveland, the study is the first to establish a link between pollution exposure and heart attacks on an hourly basis. Rajagopalan was not a participant in the study.

“With a fair degree of certainty, the authors were able to establish that air pollution levels at the hour of heart attack occurrence were substantially connected with air pollution levels during the same hour,” he stated. “This shows that adopting precautions when air pollution levels are high may help prevent heart attacks.”

In 2020, Rajagopalan co-wrote an AHA scientific statement on how to limit exposure to air pollution. Closing windows and using portable air cleaners and built-in air conditioner filters, as well as personal air-purifying respirators that cover the nose and mouth for people at high risk, are among the strategies.

According to Rajagopalan, properly fitted masks, such as those used to combat the spread of COVID-19, can also help.

One of COVID-19’s silver linings is the widespread use of N95 masks, he stated. “These are extremely effective at reducing particle exposure. They will obstruct your ability to inhale them. “

Despite the fact that this study was conducted in China, which has some of the world’s worst air quality, the findings are still relevant to other nations, according to Kan.

The fact that there was no pollution threshold—no acceptable minimum—suggests that the findings could be applicable to countries with lower levels of air pollution, such as the United States, he said. However, given the apparent disparities in air pollution characteristics and population sensitivity, the effects of individual air pollutants on ACS must be replicated.

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