We saw little temporal changes between 2003 and 2010 in noise levels and air pollution concentrations even though some major traffic policy schemes had been implemented across this period such as the Low Emission Zone in 2008 and Congestion Charging Zones in 2003 and 2007. Little temporal change across London in traffic volume, one of the most important parameters together with distance in our noise model, means that noise levels change little over time. The logarithmic scale of the noise values further suppresses any temporal variability. Air pollution levels also vary by relatively small amounts over time, even those which relate specifically to local air pollution (NOX) and traffic components of PM (PM2.5traffic, PM10traffic). For PM metrics, reductions in tail-pipe emissions have been offset by increases in the number and weight of vehicles which has resulted in a proportional increase in particulate matter from brake and tyre wear and road abrasion (Boulter, 2005). Despite little temporal change in either noise or air pollution levels potential qualitative changes in particle composition and noise characteristics due to changes in the fleet might lead to changes in associations with health.