Association between long-term ambient fine particulate matter exposure and risk of postneonatal infant mortality in Taiwan.

Infants and children may be potentially susceptible to harm from ambient fine particulate matter (PM) pollution because of the following characteristics (1) immature immune systems (2) not yet fully developed respiratory systems (3) possess a higher absorption rate of pollutants, and (4) and daily activities may expose infants to varying levels. However, few studies have examined the possible correlation between exposure to PM and mortality in infants. Therefore, the aim of this study was to investigate the association between long-term exposure to ambient PM and post-neonatal mortality in 65 municipal areas across Taiwan. The mean annual PM levels of each municipality were categorized from 2013 to 2022 and divided into tertiles. The natural logarithm of the annual post-neonatal mortality rates per 1000 live births was assessed with respect to PM level, urbanization level, physician density, and mean annual average household income. Weighted-multiple linear regression was utilized to compute the adjusted RRs and their 95% confidence intervals (CIs). When data were not stratified by PM levels, a significant positive association was observed between long-term lifetime exposure to ambient PM and post-neonatal mortality rates after adjustment for physician density, urbanization level, and average household income. When PM levels (in tertiles) were stratified, a positive but nonsignificant trend was found in post-neonatal mortality frequency from the lowest to the highest PM category. These findings suggest that long-term exposure to PM increases the risk of post-neonatal mortality rates in Taiwan.