The association of particulate matter 2.5 exposure with frailty trajectories in middle-aged and older Chinese adults and the potential modification by lifestyle and socioeconomic status.

OBJECTIVE

To examine PM2.5 exposure associations with frailty trajectories in middle-aged and older Chinese adults, and evaluate modifying effects of lifestyle and socioeconomic status (SES).

METHODS

We analyzed 10,659 participants from CHARLS using PM2.5 data from Dalhousie University. Frailty was assessed via a deficit accumulation index. Group-based trajectory modelling (GBTM) identified frailty trajectories; ordered logistic regression estimated associations and effect modifications.

RESULTS

Three trajectories emerged: "Stable low" (63.95%), "Increased to frailty" (29.00%), and "Continuously worsening" (7.05%). Each 10 μg/m³ PM2.5 increase raised odds of Trajectories 2 and 3 by 15.2% and 12.3%, respectively. Higher SES attenuated PM2.5 effects (RERI=-0.067), while unhealthy sleep duration amplified them (RERI=0.163).

CONCLUSIONS

PM2.5 exposure is associated with deteriorating frailty trajectories. Higher SES exerts an antagonistic effect, whereas unhealthy sleep duration has a synergistic effect on PM2.5-related frailty progression.