Relationship of ambient humidity with cardiovascular diseases: a prospective study of 24,510 adults in a general population

Objective: This study aimed to explore the association between humidity exposure and the risk of cardiovascular disease (CVD), utilizing follow-up data and relative humidity (RH) metric assessments.

Methods: We extracted the baseline data from the China Hypertension Survey (CHS) of 24,510 enrolled participants aged ≥ 35 years without a history of CVD between 2012 and 2015 and followed them up from 2018 to 2019. The National Meteorological Information Center (NMIC) of the China Meteorological Administration (CMA) provided the quality-controlled relative humidity (RH) datasets. Cox proportional hazards models were used to estimate hazard ratios (HRs) for CVD in relation to RH.

Results: During the follow-up period (2018–2019), 973 patients with CVD were identified. The HR of CVD risk was 1.17 (95% CI: 1.04–1.31) per 10% increase in summer mean RH. Compared with participants in the 3rd quintile group, those in the 1st and 5th quintiles of RH had a higher risk of CVD. For summer mean RH, the HRs (95% CIs) for the 1st and 5th quintiles were 1.34 (1.04–1.71) and 1.44 (1.14–1.83), respectively. The relationship (“U” shape) between summer mean RH and the risk of CVD was nonlinear. Stratified analyses indicated that the risk of CVD was substantially influenced by the summer mean RH in female, older individuals, and those in southern China.

Conclusion: Unsuitable (too high or low) humidity environments affect the risk of CVD. Our study highlights those future policies for adapting to climate change should consider the humidity–CVD relationship.