Correlations between noise and air pollution metrics do not seem to be driven by higher exposures. We only saw marginally higher correlations between noise and air pollution in the highest air pollution tertiles. Distance from road had also little effect on correlations. Stratified analysis by Inner London and Outer London indicated that the observed patterns in correlation across London overall are not a central London effect where both noise and air pollution are higher. Slightly stronger correlations tend to be seen where there is more variability in exposures, hence the stronger correlations seen in the highest exposure band and more noticeably across all postcodes in London.