We used Spearman's rho to assess correlations between noise and air pollution metrics, which is a non-parametric measure of dependence between two variables based on case rankings and suitable to assess correlations for variables with skewed distributions. We also calculated Pearson's correlations of log transformed noise and air pollution levels for comparison reasons. We excluded postcodes with either missing noise estimates (0.3%), as a result of the receptor placement issues in the noise model (for more information see Gulliver et al., 2015); or air pollution estimates (0.004%), locations outside the air pollution modelling domain.