PM(2.5)-Associated Hospitalization Risk of Cardiovascular Diseases in Wuhan: Cases Alleviated by Residential Greenness

PM(2.5), a type of particulate matter with an aerodynamic diameter of less than 2.5 μm, is associated with the occurrence of cardiovascular diseases (CVDs), while greenness seems to be associated with better cardiovascular health. We identified 499,336 CVD cases in Wuhan’s 74 municipal hospitals between 2017 and 2019. A high-resolution PM(2.5) model and a normalized difference vegetation index (NDVI) map were established to estimate individual exposures. The time-stratified case-crossover design and conditional logistic regression models were applied to explore the associations between PM(2.5) and CVDs under different levels of environmental factors. Greenness could alleviate PM(2.5)-induced hospitalization risks of cardiovascular diseases. Compared with patients in the low-greenness group (ER = 0.99%; 95% CI: 0.71%, 1.28%), patients in the high-greenness group (ER = 0.45%; 95% CI: 0.13%, 0.77%) showed a lower increase in total CVD hospitalizations. After dividing the greenness into quartiles and adding long-term PM(2.5) exposure as a control factor, no significant PM(2.5)-associated hospitalization risks of CVD were identified in the greenest areas (quartile 4), whether the long-term PM(2.5) exposure level was high or low. Intriguingly, in the least green areas (quartile 1), the PM(2.5)-induced excess risk of CVD hospitalization was 0.58% (95% CI: 0.04%, 1.11%) in the long-term high-level PM(2.5) exposure group, and increased to 1.61% (95% CI: 0.95%, 2.27%) in the long-term low-level PM(2.5) exposure group. In the subgroup analysis, males and participants aged 55–64 years showed more significant increases in the PM(2.5)-induced risk of contracting CVDs with a reduction in greenness and fine particle exposure conditions. High residential greenness can greatly alleviate the PM(2.5)-induced risk of cardiovascular admission. Living in the areas with long-term low-level PM(2.5) may make people more sensitive to short-term increases in PM(2.5), leading to CVD hospitalization.