Exposure Assessment
Exposure measurements
Instrumented pedestrians and cyclists traveled through the study area measuring fine particle and CO exposure, with additional data from video output from the Health and Safety Laboratory instrumentation and GPS from NERI and UCL. All workers wore yellow vests with a DAPPLE air pollution badge for easy recognition. Volunteers also carried information and contact details, for distribution should they be stopped.
The aims of the exposure work were to investigate:
- smaller scales of pedestrian exposure variation i.e. across the pavement, walking with and against the traffic, walking on different sides of the road (DAPPLE 2003 concentrated on differences between modes of transport) - data from DAPPLE 2004 exposure will help quantify and explain the variance of the DAPPLE 2003 exposure results;
- static exposure sites close to other fixed instrumentation to aid comparison between data sets - i.e. data from below lamppost on which streetboxes were mounted to obtain vertical CO gradients;
- vertical gradients from ground to head height at fixed locations next to the mobile, sites 11 and 12, sonic anemometers;
- cyclist exposure and the use of the HSL video imagery equipment;
- whether or not GPS can be used to track exposure volunteers as they move through an urban area.
Mobile sonic anemometry
Ground level "mobile" ultrasonic anemometers - mobile in that they could be deployed on 1.5 m stands when and where required, depending on activity and wind direction - were used to investigate ground levels flows in support of the exposure and tracer release work. The aims were to investigate:
