Fig. 3: Relationships between PM2.5 exposure and vascular dementia (six data points from six studies).

a, RR function. The solid green line represents the mean RR at each exposure level. The dark green shaded area indicates the 95% UI without accounting for between-study heterogeneity, while the light green shaded area represents the 95% UI accounting for between-study heterogeneity. The size of the data points is proportional to the inverse of the s.d. of the effect estimates, where larger points indicate higher precision in the effect estimates. b, A modified funnel plot showing the residuals (relative to zero) on the x axis and the estimated s.d. (inclusive of between-study heterogeneity) on the y axis.