Long-Term Ambient PM_2.5 Exposure and Premature Mortality Across of Türkiye

Long-term exposure to ambient fine particulate matter (PM_2.5) is the leading environmental risk factor for premature mortality worldwide, yet comprehensive province-level evidence quantifying its health burden across Türkiye remains limited. This study investigated the spatial relationship between long-term PM_2.5 exposure and all-cause attributable mortality across all 81 Turkish provinces in 2022 using province-level annual mean PM_2.5 concentrations and World Health Organisation (WHO) AirQ+ estimates of PM_2.5-attributable deaths among adults aged ≥30 years, assuming a counterfactual concentration of 5 µg/m³. The association between PM_2.5 exposure and mortality was evaluated using Pearson and Spearman correlation analyses, ordinary least squares (OLS) regression, a log-log elasticity model, and population-weighted regional and exposure-quartile comparisons, while national temporal indicators for 2010-2023 were reported solely as supplementary context for the primary single-year 2022 cross-sectional analysis. The population-weighted annual mean PM_2.5 concentration was 27.0 µg/m³, exceeding the WHO Air Quality Guideline by a factor of 5.4, and all 81 provinces exceeded the recommended threshold. The bivariate OLS model accounted for 41% of the between-province variation in attributable mortality rates (OLS slope = 3.23 additional deaths per 100,000 population for each 1 µg/m³ increase in PM_2.5; 95% CI: 2.37-4.10; R² = 0.41; p < 0.001), while the log-log elasticity model indicated that a 1% increase in PM_2.5 concentration was associated with a 0.80% increase in the attributable mortality rate (95% CI: 0.65-0.95). The attributable fraction of natural-cause mortality increased progressively from 8.8% in the lowest exposure quartile to 24.6% in the highest. Nationwide, an estimated 68,440 premature deaths, representing 14.2% of all natural-cause deaths among adults aged ≥30 years, were attributable to PM_2.5 exposure. These findings quantify a steep, spatially graded PM_2.5-attributable mortality burden across Türkiye. As the attributable estimates derive from the WHO AirQ+ concentration-response function, the gradient describes the magnitude and spatial distribution of the modelled burden rather than an independently estimated exposure-response relationship, and on that basis the results support the adoption of WHO-aligned air-quality standards and accelerated decarbonization strategies to reduce the national health burden attributable to ambient air pollution.