Fig. 1
The concentration-response curves of fine particulate matter (PM2.5) concentrations (degree of freedom = 3) and outpatient visits and inpatient visit for chronic obstructive pulmonary disease (COPD) between January 1, 2010, and June 30, 2012, in Beijing, China. Note: The X-axis is the concurrent day PM2.5 concentrations (μg/m3), Y-axis is the predicted log (relative risk (RR)), is shown by the solid line, and the dotted lines represent the 95% CI