Ambient PM2.5 and acute incidence of myocardial infarction in China: a case-crossover study and health impact assessment

Abstract:

Since evidence investigating the association between ambient PM_2.5 and acute incidence of myocardial infarction is limited, this study aims to investigate linear and non-linear patterns for the association between PM_2.5 and acute incidence of myocardial infarction, and evaluate the reduction of premature myocardial infarction incidence under different pollution control objectives in China. 36,679 registered myocardial infarction incidence cases from 15 Chinese counties during January 1, 2013 to December 31, 2017 were obtained. We adopted a time-stratified case-crossover design with conditional logistic regression models. Avoided premature morbidity attributed to per 10μg/m³ reduction of exposure was estimated. With a 10 μg/m³ increase in exposure, there was an increase of 0.98% (0.40%, 1.57%) in acute incidence risk of myocardial infarction. The corresponding values for males and individuals aged over 74 years were 1.58% (95% CI: 0.82%, 2.35%) and 1.19% (95% CI: 0.35%, 2.05%) respectively, indicating higher risks than other groups. The nonlinear concentration-response curve indicated a steeper slope under daily exposure below 50μg/m³ and the marginal avoided premature morbidity became larger under the current air quality standard. The robust findings from this study may suggest the necessity for a continuous reduction of exposure concentration from the perspectives of public health.