Very strong correlations between postcode level estimates within LSOAs cannot be explained by the presence or absence of major roads because we did not find any associations between correlations and either road density or vehicle kilometres (r = | 0.00–0.17 |). We also did not find any association between the direction and magnitude of postcode level correlations between noise and air pollution metrics within LSOAs and the socio-economic status of the LSOA (r = | 0.01–0.15 |).