A South Korean study has found that the link between short-term exposure to fine particulate matter (PM2.5) and cardiovascular disease among cancer survivors disappeared during the COVID-19 pandemic. The findings, published in an international academic journal, highlight how changes in everyday living environments can significantly affect health outcomes—especially for vulnerable populations such as cancer survivors.
The joint research team from Seoul St. Mary’s Hospital and Seoul National University Hospital—led by Professor Shin Hyun-young (Seoul St. Mary’s), researcher Lee Hyuk-jong (Seoul National University), and corresponding author Professor Park Sang-min (Seoul National University Hospital)—analyzed data from the National Health Insurance Service. The study examined 39,581 individuals who had survived more than three years after a cancer diagnosis.
Focusing on patients newly diagnosed with cardiovascular disease (myocardial infarction or stroke) after 2015, the team used a time-stratified case-crossover design to analyze the causal relationship between PM2.5 exposure and cardiovascular events. Prior to the social distancing measures implemented on March 22, 2020, the study found that every 10 μg/m³ increase in daily average PM2.5 concentration was associated with a roughly 3% rise in cardiovascular risk. Among the highest exposure group (44.99±15.05 μg/m³), the risk increased by approximately 9%, with significant elevations in the risks of myocardial infarction (10%) and ischemic stroke (11%).
However, following the implementation of pandemic-related restrictions—including mask mandates, remote work, and reduced outdoor activities—the statistical link between PM2.5 exposure and cardiovascular events disappeared. Researchers attribute this to both decreased individual exposure and improved air quality resulting from reduced industrial activity and traffic during the pandemic.
“Cancer survivors are particularly sensitive to environmental changes,” said Professor Park. “Regular precautions such as avoiding outdoor activities on high-pollution days and wearing masks can substantially lower their risk of cardiovascular disease.”
Professor Shin added, “Inhalation of fine particulate matter can alter the gut microbiome, promote pulmonary and systemic inflammation, and impair endothelial function—all of which contribute to elevated cardiovascular risk. This study underscores the need for environmental health policies targeting vulnerable populations like the elderly and those with chronic conditions.”
The study is notable for using cancer survivors—a uniquely vulnerable group—to examine the real-world health impact of a major social intervention. Researcher Lee emphasized that the time-stratified design allowed for a robust comparison between pre- and post-COVID periods, enhancing the statistical reliability of the results.
The findings reaffirm the importance of environmental management for public health, particularly in protecting those most at risk.
