Daily changes in fine particulate matter are associated with acute myocardial infarction hospitalizations: an individual-level time-stratified case-crossover study in Zhongshan, China.
Zeng H, Li X, et al. • Frontiers in public health • 2026
Daily increments in ambient PM2.5 concentration were independently associated with an increased risk of AMI hospitalization, particularly among females, older adults, and patients with ST-segment elevation myocardial infarction.
Key Findings
Results
A 10 μg/m³ increase in PM2.5 from the previous day to the admission day was associated with a 7.89% higher odds of AMI hospitalization.
The association was observed at the lag0-lag1 window (day-to-day change from previous day to admission day)
95% CI: 0.86%–15.40%
Study period: 2020–2024 in Zhongshan, China
1,795 AMI hospitalizations identified from a tertiary hospital, with 5,877 matched control days
Individual-level time-stratified case-crossover design using conditional logistic regression
Results
Female patients showed a stronger association between daily PM2.5 increases and AMI hospitalization compared to the overall population.
A 10 μg/m³ day-to-day increase in PM2.5 was associated with 22.58% higher odds of AMI hospitalization among females
Subgroup analysis was performed by age, sex, season, AMI subtype, and comorbidities
Age was identified as a significant effect modifier (P for interaction < 0.05)
Results
Adults aged over 65 years showed a stronger association between daily PM2.5 increases and AMI hospitalization than the overall cohort.
A 10 μg/m³ day-to-day increase in PM2.5 was associated with 22.16% higher odds of AMI hospitalization in adults >65 years
Age was a statistically significant effect modifier (P for interaction < 0.05)
This subgroup analysis was pre-specified alongside sex, season, AMI subtype, and comorbidities
Results
Patients with ST-segment elevation myocardial infarction (STEMI) showed a stronger association with day-to-day PM2.5 increases compared to the overall AMI population.
A 10 μg/m³ day-to-day increase in PM2.5 was associated with 17.90% higher odds of AMI hospitalization among STEMI patients
Subgroup analysis distinguished STEMI from other AMI subtypes
Results were part of pre-specified subgroup analyses
Results
Cold-season admissions showed a stronger association between daily PM2.5 increases and AMI hospitalization risk.
A 10 μg/m³ day-to-day increase in PM2.5 was associated with 10.85% higher odds of AMI hospitalization during the cold season
Seasonal subgroup analysis was one of five pre-specified subgroup analyses
Models adjusted for temperature, relative humidity, and public holidays
Results
Results were robust to adjustment for co-pollutants and alternative model specifications, with the exception of nitrogen dioxide adjustment.
Sensitivity analyses included adjustment for co-pollutants
Results remained robust after using alternative degrees of freedom (df) for temperature and relative humidity splines
The association was attenuated or no longer statistically significant after adjustment for nitrogen dioxide specifically
PM2.5 exposure was assigned using the China High Air Pollutants (CHAP) dataset at 1 km resolution based on residential address
Methods
The study used an individual-level time-stratified case-crossover design with high-resolution satellite-derived PM2.5 exposure data.
Control days were matched by day of week within the same calendar month to control for time-varying confounders
PM2.5 exposure was assigned at 1 km spatial resolution using the CHAP dataset
1,795 AMI hospitalizations and 5,877 control days were included from 2020 to 2024
Both absolute PM2.5 concentration and day-to-day change were evaluated as exposures
What This Means
This research suggests that sudden increases in air pollution from one day to the next may raise the risk of being hospitalized for a heart attack. The study tracked over 1,700 heart attack hospitalizations in Zhongshan, China over four years and found that when fine particle air pollution (PM2.5) rose by 10 micrograms per cubic meter from one day to the next, the odds of a heart attack hospitalization increased by about 8%. This is notable because most prior research focused only on total pollution levels, not how rapidly pollution changes day to day.
Certain groups appeared particularly vulnerable to these day-to-day pollution swings. Women, people over 65 years old, and patients with a specific severe type of heart attack (STEMI) all showed roughly double the risk increase compared to the overall group. Cold-season hospitalizations also showed elevated risk. Age was statistically confirmed as a meaningful factor modifying the relationship between pollution changes and heart attack risk.
This research suggests that daily fluctuations in air pollution — not just chronic high pollution levels — may independently contribute to acute cardiac events. These findings could be relevant to public health early-warning systems and cardiovascular prevention strategies, particularly for older adults and other vulnerable populations who may benefit most from alerts when air quality is deteriorating rapidly.
Zeng H, Li X, Zhao Y, Xu J, Wei J. (2026). Daily changes in fine particulate matter are associated with acute myocardial infarction hospitalizations: an individual-level time-stratified case-crossover study in Zhongshan, China.. Frontiers in public health. https://doi.org/10.3389/fpubh.2026.1911027