Introduction The built environment is constantly changing. Whether it be short-term changes - e.g. roadworks, or long-term, e.g. a new road. These changes can impact exposures (air pollutants from road traffic), behaviours (decision to drive to work) or health (risk of being in a traffic accident). It’s therefore important to monitor the changes to the built environment so that interventions can be developed to reduce risk to health either directly or indirectly (exposure/behaviour).