We explored Spearman's rho correlations between noise and air pollution metrics (mean for 2003–2010) across postcodes within London, across postcodes within London Boroughs, across postcodes within LSOAs and across postcodes within 1 km × 1 km grid cells. We used Moran's I to assess whether there were geographical patterns in correlations across LSOAs and 1 km × 1 km grid cells. For selected air pollutants (PM2.5traffic, PM10, NOX, O3), we explored correlations with noise metrics for postcodes within different exposure categories (tertiles); different distances to major roads (≤ 50 m, ≤ 100 m, ≤ 200 m from major roads with more than 10,000 vehicles per day); different deprivation bands (tertiles); and within Central London only (defined by the Inner London Boroughs, see Supplemental Fig. S1).