Ambient air pollution and risk of hospital admission due to acute and chronic coronary syndromes: a time-stratified case-crossover study in the 3 largest urban agglomerations in Poland

INTRODUCTION: Short‑term exposure to air pollution may worsen the course of ischemic heart disease (IHD), causing acute and chronic coronary syndromes. OBJECTIVES: This study aimed to assess the risk of hospital admission due to chronic coronary syndromes (CCSs) and acute coronary syndromes (ACSs) after exposure to various air pollutants in Poland. METHODS: This time‑series study evaluated the risk of hospital admission due to IHD over 3 days from exposure to several air pollutants. A distributed lag nonlinear modelling was used to determine the counts of hospital admissions due to CCSs and ACSs. Data for the 3 largest urban agglomerations in Poland between 2012 and 2017 were collected. RESULTS: Within the study period, there were 88 467 admissions due to CCSs and 35 403 admissions due to ACSs. After adjusting for meteorological variables, the risk of admission due to CCSs increased after the exposure to particulate matter (PM) of aerodynamic diameter no greater than 10 μm (PM10; cumulative rate ratio [CRR] per 10 μg/m3, 1.007; 95% CI, 1.002-1.012), of diameter no greater than 2.5 μm (PM2.5; CRR per 10 μg/m3, 1.008; 95% CI, 1.001-1.014), and NO2 (CRR per 10 μg/m3, 1.037; 95% CI, 1.026-1.047). The risk of admission due to ACSs was increased after exposure to PM10 (CRR per 10 μg/m3, 1.009; 95% CI, 1.002-1.015) and PM2.5 (CRR per 10 μg/m3, 1.009; 95% CI, 1.001-1.018), whereas the association for the gaseous pollutants, NO2 and SO2, was less pronounced, that is, CRR per 10 μg/m3, 1.012; 95% CI, 0.998-1.026 and CRR per 10 μg/m3, 1.032; 95% CI, 0.998-1.067, respectively. CONCLUSION: The exposure to PM10, PM2.5, and NO2 is associated with an increased short‑term risk of hospital admission due to ACSs and CCSs.