Fig. 1
Spatial covariates tested as potential predictors of the heterogeneity in hospitalisation incidence. PM2.5 refers to particulate matter of ≤ 2.5 μm. Median declared income is expressed in euros (€) and was averaged over each HCA (see the Methods section in Additional file for further detail). Mean concentration of particulate matter of ≤ 10 μm (PM10) and proportion of people who are more than 65 years old are not represented but are highly correlated with mean PM2.5 concentration and median age, respectively