Fig. 2
Non-linear relationships between longevity measures and PM2.5. Panels a and b present the relationship between exceptional aging and PM2.5 for the unadjusted and fully adjusted models, respectively. Panels c and d present the relationship between life expectancy and PM2.5 for the unadjusted and fully adjusted models, respectively. Spline smooth functions allowed for up to four degrees of freedom. Unadjusted models exclude controls for smoking and obesity, while full models include these controls