Fig. 3.
Sensitivity of national average estimate of the smooth seasonal effects of a 10 μg/m3 increase of particulate matter less than 10 μm in aerodynamic diameter (PM10) at a lag 01 day to the degrees of freedom assigned for the smooth function of time in the China Air Pollution and Health Effects Study (CAPES). The degrees of freedom selected were 4 df (dashed line), 7 df (solid line) and 10 df (dotted line).