Effect of short-term fluctuations in outdoor air pollution on the number of hospital admissions due to acute myocardial infarction among inhabitants of Kraków, Poland

INTRODUCTION Air pollution is reaching alarming proportions worldwide; however, previous studies concerning the association between air pollution and myocardial infarction (MI) provided conflicting results.
OBJECTIVES We evaluated a relationship between short‑term fluctuations in outdoor particulate matter (PM) and nitrogen dioxide (NO2) levels and the number of hospitalizations due to MI among the inhabitants of Kraków, Poland.
PATIENTS AND METHODS Data on hospitalizations, daily pollutant concentrations, infections, and meteorological parameters were collected from December 2012 to September 2015. Data were assessed using a time‑series regression analysis with a distributed lag model.
RESULTS An increase of 10 μg/m3 in PM2.5 levels was associated with a higher risk of hospital admission due to MI (odds ratio [OR], 1.32; 95% CI, 1.01–1.40; P = 0.0002). For PM10 the effect was observed only with a simultaneous decrease of 1ºC in the mean daily temperature (OR, 1.08; 95% CI, 1.01–1.17; P = 0.03). Significant effects were observed at lags 5 and 6. The effect of NO2 was significant at lags 0 and 1, but only in patients aged 70 years or older (OR, 1.13; 95% CI, 1.01–1.23; P = 0.007) and those with pulmonary disorders (OR, 1.12; 95% CI, 1.01–1.31; P = 0.01).
CONCLUSIONS In all age groups, the short‑term elevation in PM2.5 levels was associated with an increased number of daily hospital admissions for MI, whereas for PM10 the effect was significant only with a simultaneous decrease in temperature. The effect of NO2 was observed only in older individuals
and patients with pulmonary disorders. A negative clinical effect was more delayed in time in the case of exposure to PM than to NO2.