Trends in PM₂.₅ and mortality risks in an industrial District of Taiwan: a 12-year analysis

Ambient air pollution, particularly fine particulate matter (PM₂.₅), poses a major global public health concern. We examined trends in all-cause and respiratory disease-specific mortality and their association with PM₂.₅ concentrations during three time periods (2008-2011, 2012-2015, 2016-2019) in Linyuan District, Kaohsiung City, and Taiwan, using generalized Poisson mixed models. PM₂.₅ concentrations declined by 23.6% in Taiwan, from 24.5 µg/m³ (2008-2011) to 18.8 µg/m³ (2016-2019), with similar reductions observed in Kaohsiung City and Linyuan District. Age-standardized all-cause mortality rates also decreased over time. Nevertheless, residents of Linyuan consistently exhibited higher mortality than those in Kaohsiung City and Taiwan. Each 1 µg/m³ increase in PM₂.₅ was associated with higher all-cause mortality risk (men: RR = 1.011, 95% CI: 1.001-1.021; women: RR = 1.017, 95% CI: 1.004-1.031). Despite overall declines in PM₂.₅ and mortality rates, excess risks persist in heavily industrialized areas. These findings highlight the public health benefits of air-quality improvements and the need for sustained pollution control efforts. In addition, as this study is observational and ecological in nature, the findings should be interpreted with caution and not as evidence of causality.