Air pollution is a consequence of industrial development that is exacerbated as a result of population growth, and urbanisation.

The goal of the study is to investigate the effects of air pollution on the number of cases of acute myocardial infarction (AMI) according to gender using the Zero-inflated Poisson Regression model in Hamadan, Iran.

The study used an ecological design, and data collected from March 2016 to September 2020 in Hamadan were included. The intended response was the number of cases of AMI recorded in the investigated period. The time lag of the pollutants was used to investigate the effect of air pollution on the number of AMIs.

The number of AMI recorded for men and women was 1,195 and 553, respectively. The average age (±SD) for men and women was 64.60 (±12.27) and 70.98 (±11.79) years, respectively. According to the air quality index in Hamadan, the values of particulate matter < 2.5 μm (PM_2.5), SO₂, O₃, and CO were below moderate levels. Also, according to NO₂ and particulate matter between 25 μm–10 μm (PM₁₀), the air quality index of Hamadan was in the very unhealthy mode just for 2 and 3 days, respectively. The O₃ and NO₂ are significant positive effects on AMI among men. But, PM_2.5, PM₁₀, and SO₂ are negative impacts on hospitalisation in men due to AMI. For women, PM_2.5 and O₃ had positive effects on AMI. But, NO₂ and PM₁₀ had a significant negative impact on hospitalisation in women during different time lags.

The results of the study showed that if the analyses are based on gender, the responses to pollutants are different and hence the stratified analysis is important.