Using data from South Korea’s National Health Insurance Service, the researchers examined 39,581 cancer survivors diagnosed between 2009 and 2018 who survived at least three years post-diagnosis. Focusing on new cases of myocardial infarction and ischemic stroke diagnosed after 2015, the team applied a time-stratified case-crossover design to assess the short-term impact of PM2.5 exposure on cardiovascular events.
Before the implementation of COVID-19 social distancing measures, a 10 μg/m³ increase in PM2.5 concentration was associated with a 3% rise in cardiovascular event risk. In the highest exposure group, the risk increased by 9%, with myocardial infarction and ischemic stroke risks rising by 10% and 11%, respectively. These findings were statistically significant, particularly among cancer survivors, who are especially susceptible to environmental stressors.
However, after social distancing measures began in March 2020, the association between PM2.5 exposure and cardiovascular events weakened to statistical insignificance. The researchers attribute this to reduced personal exposure through mask-wearing, remote work, and limited outdoor activities, as well as lower ambient PM2.5 levels due to decreased global industrial activity and traffic.
“This study is a landmark in quantifying the cardiovascular risks of short-term PM2.5 exposure in cancer survivors, a group highly sensitive to environmental changes,” said Dr. Sang-Min Park, professor of family medicine at Seoul National University Hospital and the study’s corresponding author. “Our findings indicate that practical measures, such as wearing masks and avoiding outdoor activities on high-pollution days, can substantially reduce cardiovascular risks for this population.”
Dr. Hyeon-Yeong Shin, professor of family medicine at Seoul St. Mary’s Hospital and co-first author, highlighted the underlying mechanisms. “PM2.5 promotes systemic inflammation, which heightens cardiovascular risk,” she said. “For cancer survivors, integrating environmental considerations into health management is critical for holistic care.”
The study also underscores the broader implications of environmental shifts. The global reduction in PM2.5 levels during the pandemic—driven by lower industrial output and vehicular emissions—served as a natural experiment, demonstrating how cleaner air can mitigate health risks. The researchers capitalized on this context to compare pre- and post-pandemic outcomes with precision, leveraging large-scale national data.
“We treated the pandemic as a natural experiment, enabling us to rigorously evaluate changes in PM2.5’s health impacts,” said Hyeok-Jong Lee, a researcher at Seoul National University’s Department of Biomedical Sciences and co-first author. “The granularity of our data supported a robust comparison of these effects.”
Classified by the World Health Organization as a Group 1 carcinogen, PM2.5 poses a well-documented threat to public health. This study emphasizes its acute risks for immunocompromised populations like cancer survivors while illustrating how environmental interventions can yield tangible health benefits. The researchers hope their findings will guide tailored environmental policies for other vulnerable groups, such as the elderly and those with chronic conditions.
Looking ahead, the team plans to explore the causal pathways linking PM2.5 exposure to cardiovascular events and to develop actionable policy recommendations. “Our aim is to advance this work to inform precision environmental health strategies,” Dr. Park said.
Health In News Team Lim Hye Jeong
press@hinews.co.kr