Masks and Heart Attacks: How Pandemic Habits May Have Lowered Risk of a Specific Cardiac Event
Researchers at Kumamoto University have discovered that behavioral changes during the COVID-19 pandemic—particularly widespread mask-wearing—may have reduced the risk of myocardial infarction with non-obstructive coronary arteries (MINOCA), a specific type of heart attack triggered by air pollution. The study, led by Dr. Masanobu Ishii and colleagues, was published in the European Heart Journal.
Air Pollution and Heart Attacks: A Known Risk
Fine particulate matter known as PM2.5—tiny airborne particles little enough to penetrate deep into the lungs—has long been recognized as a major environmental risk factor for cardiovascular disease. Exposure can trigger inflammation, oxidative stress, and blood vessel dysfunction, potentially leading to acute myocardial infarction (AMI), commonly known as a heart attack. Research has shown that short-term exposure to PM2.5 increases the risk of AMI.
The Study: Analyzing Heart Attack Data During and Before COVID-19
Using Japan’s nationwide cardiovascular database (JROAD-DPC), the research team analyzed data from 270,091 patients hospitalized for AMI between 2012, and 2022. They examined short-term exposure to PM2.5 and compared risks before and during the COVID-19 pandemic, which brought dramatic shifts in public behavior, including mask use and reduced mobility.
MINOCA: A Particularly Vulnerable Heart Attack Subtype
The researchers found that short-term exposure to PM2.5 significantly increased the risk of all types of AMI. However, MINOCA—a heart attack without coronary artery obstruction—showed a particularly strong association with air pollution.
Pandemic-Related Decline in MINOCA Risk
Most notably, after the onset of the pandemic, the PM2.5-related risk of MINOCA significantly declined. In contrast, the risk of the more typical heart attack with coronary artery obstruction (MI-CAD) remained largely unchanged. Specifically, a 10 µg/m3 increase in PM2.5 two days before admission was associated with a 1.151 times higher odds ratio for MINOCA before the pandemic (95% confidence interval 1.079-1.227), but this association was reduced after the pandemic began.
How Mask-Wearing May Have Protected Against MINOCA
The findings suggest that pandemic-related preventive behaviors—especially mask-wearing—may have reduced individual exposure to harmful particulate matter, thereby lowering the risk of pollution-triggered vascular dysfunction such as coronary spasm or microvascular impairment.
Implications for Public Health and Future Prevention
This study provides real-world evidence that simple protective measures can mitigate cardiovascular risks associated with unavoidable environmental exposures. Even in Japan, where no strict lockdowns were imposed, voluntary public health practices appear to have delivered measurable cardiovascular benefits. The researchers emphasize that improving air quality remains a long-term priority. However, the findings also highlight the potential of accessible interventions—such as mask use during high-pollution periods—to protect vulnerable populations.
As societies confront ongoing environmental challenges, these insights may help shape future preventive cardiology and public health strategies worldwide.