The impact of monthly air pollution exposure and its interaction with individual factors: Insight from a large cohort study of comprehensive hospitalizations in Guangzhou area.

Background: Although the association between short-term air pollution exposure and certain hospitalizations has been well documented, evidence on the effect of longer-term (e. g., monthly) air pollution on a comprehensive set of outcomes is still limited.

Method: A total of 68,416 people in South China were enrolled and followed up during 2019-2020. Monthly air pollution level was estimated using a validated ordinary Kriging method and assigned to individuals. Time-dependent Cox models were developed to estimate the relationship between monthly PM and O exposures and the all-cause and cause-specific hospitalizations after adjusting for confounders. The interaction between air pollution and individual factors was also investigated.

Results: Overall, each 10 μg/m increase in PM concentration was associated with a 3.1% (95%: 1.3%-4.9%) increment in the risk of all-cause hospitalization. The estimate was even greater following O exposure (6.8%, 5.5%-8.2%). Furthermore, each 10 μg/m increase in PM was associated with a 2.3%-9.1% elevation in all the cause-specific hospitalizations except for those related to respiratory and digestive diseases. The same increment in O was relevant to a 4.7%-22.8% elevation in the risk except for respiratory diseases. Additionally, the older individuals tended to be more vulnerable to PM exposure ( : 0.002), while the alcohol abused and those with an abnormal BMI were more vulnerable to the impact of O ( : 0.052 and 0.011). However, the heavy smokers were less vulnerable to O exposure ( : 0.032).

Conclusion: We provide comprehensive evidence on the hospitalization hazard of monthly PM and O exposure and their interaction with individual factors.