Abstract
Background Ambient fine particulate matter (PM₂.₅) is an established environmental risk factor for cardiovascular disease, yet evidence regarding its short-term effects on cardiovascular mortality remains limited in Central Asia. This study investigated the short-term association between PM₂.₅ exposure and cardiovascular mortality in Almaty, Kazakhstan. Methods We conducted a retrospective ecological time-series study using daily cardiovascular mortality and environmental data collected between January 1, 2017 and December 31, 2025 (3,287 days). Distributed lag nonlinear models within a generalized additive model framework with a quasi-Poisson distribution were used to estimate lag-specific (0–7 days) and cumulative associations between daily PM₂.₅ concentrations and cardiovascular mortality while adjusting for long-term trends, day of the week, and nonlinear temperature effects. Stratified analyses were performed by age and sex. Results During the study period, 43,095 cardiovascular deaths were recorded. The mean daily PM₂.₅ concentration was 36.9 ± 33.3 μg/m 3 . Neither lag-specific nor cumulative associations between PM₂.₅ exposure and cardiovascular mortality reached statistical significance. Relative risk estimates increased after exposure, peaking approximately 2–4 days later before declining. The cumulative relative risk for the overall population was 1.011 (95% CI, 0.837–1.222). Adults aged ≥65 years exhibited the highest cumulative relative risk estimate (RR 1.174, 95% CI, 0.926–1.489), although all subgroup confidence intervals included the null value. Conclusion Short-term PM₂.₅ exposure was not significantly associated with cardiovascular mortality in Almaty; however, the observed delayed temporal pattern was biologically plausible and suggested greater susceptibility among older adults.