Evaluation of the relationship between Air Health Index and the risk of cardiovascular and cerebrovascular disease mortality in Huizhou City: a cross-sectional study.

Introduction: Air pollution exposure is recognised to exacerbate cardiovascular diseases (CVD). This study aims to establish a localised Air Health Index (AHI) based on Huizhou City's regional data, investigate its association with CVD mortality and assess the related health risks. Methods: Data on atmospheric pollutants, meteorological conditions and CVD mortality (51 952 records) in Huizhou from 2015 to 2021 were collected. A generalised additive model was used to analyse the association between AHI and CVD mortality. Results: A significant lagged association was observed between AHI and CVD mortality risk. For the optimal single-day lag, the relative risks for the total population, individuals aged ≥65 years, males and females were 1.007 (95% CI 1.002 to 1.011), 1.008 (95% CI 1.003 to 1.013), 1.008 (95% CI 1.003 to 1.014) and 1.009 (95% CI 1.003 to 1.015), respectively (all p<0.05). For the optimal cumulative lag, the corresponding relative risks were 1.012 (95% CI 1.005 to 1.019), 1.012 (95% CI 1.004 to 1.021), 1.012 (95% CI 1.004 to 1.019) and 1.011 (95% CI 1.001 to 1.021) (all p<0.05). Attributable fraction analysis showed that AHI accounted for 6.6% (95% CI 0.6% to 12.3%) of CVD mortality in the total population, with a higher burden among those aged ≥65 years (9.2%) and among females (9.8%) compared with males (3.5%). Conclusion: The localised AHI developed in this study effectively captures the association between air pollution and CVD mortality in Huizhou, particularly among individuals aged ≥65 years. The attributable burden highlights its public health relevance and supports targeted interventions.