Short-term associations between ambient air pollution and cardiovascular disease mortality: an 11-year time-series study in Nanning, China
Abstract
Background Short-term exposure to ambient air pollution has been associated with cardiovascular disease (CVD) mortality, but localized evidence from subtropical cities in southwestern China remains limited. This 11-year time-series study aimed to evaluate the short-term associations between six criteria air pollutants and daily CVD mortality in Nanning, China. Methods We conducted a time-series analysis using daily data on CVD mortality, air pollutant concentrations, and meteorological variables from 2014 to 2024 in Nanning. Generalized additive quasi-Poisson models were used to estimate associations across single-day lags (lag0-lag7) and cumulative lag windows (lag0-1 to lag0-7), adjusting for long-term trends, temperature, relative humidity, and day of the week. Exposure-response relationships were assessed using natural cubic splines. Stratified analyses were conducted by season and age group, and two-pollutant models and sensitivity analyses were performed to evaluate robustness. Results A total of 87,913 CVD deaths were recorded during the study period, of which 57.5% occurred in males and 77.9% occurred among individuals aged ≥65 years. In single-day lag models, PM2.5, PM10, SO2, NO2, and O3-8h showed significant positive associations with CVD mortality at early lag days. At lag0, the RRs were 1.014 (95% CI: 1.008–1.020) for PM2.5, 1.009 (95% CI: 1.006–1.013) for PM10, and 1.018 (95% CI: 1.011–1.026) for NO2, while SO2 showed its largest estimate at lag1 [RR = 1.044 (95% CI: 1.018–1.069)]. In cumulative lag models, PM2.5, PM10, SO2, NO2, and O3-8h showed significant cumulative associations, whereas CO was significant mainly in shorter lag windows. Season-stratified analyses suggested pollutant-specific variation between cold and warm seasons, although formal pollutant-by-season interaction tests were not statistically significant. Age-stratified analyses indicated broader susceptibility among older adults. The main associations were generally robust in sensitivity analyses, distributed lag models, and two-pollutant models, particularly for PM2.5, PM10, and NO2. Conclusion Short-term exposure to ambient air pollution was associated with increased CVD mortality, particularly for PM2.5, PM10, and NO2, with consistent effects across single-day and cumulative lag structures. The results highlight the cardiovascular risks of particulate and traffic-related pollution and support pollutant-specific air quality management and targeted protection for older adults during high-pollution periods.