Thermal inversion and risk of incident cardiovascular disease in China: a national cohort study

Thermal inversion may exacerbate pollutant accumulation and elevate cardiovascular risk, yet its health impacts remain inadequately defined. We conducted a secondary analysis using data from the China Health and Retirement Longitudinal Study, which followed 7,865 participants from 2011 to 2020. Annual mean inversion intensity (AMII) and inversion occurrence were estimated using MERRA-2 reanalysis data at 850–1000 hPa and 700–1000 hPa pressure layers. Cox proportional hazards models, restricted cubic splines, and Local Moran’s I statistics were employed to assess exposure–response associations and spatial clustering. During follow-up, 1,803 participants (22.9%) developed cardiovascular disease (CVD). Compared to unexposed individuals, annual inversion occurrence was associated with a 61–62% increased risk of CVD. Spatial analysis revealed significant clustering of high CVD risk in central and eastern China. Participants in the highest quartile of AMII (850–1000 hPa) had a 56% higher risk of CVD compared to those in the lowest quartile. A J-shaped relationship was observed, with CVD risk increasing sharply above −1.08 °C (850–1000 hPa) and −2.80 °C (700–1000 hPa), corresponding to 190% and 62% risk increases, respectively. These findings support incorporating inversion monitoring into warnings and policies, offering a new meteorological angle on CVD risk.