The Citizen Sense team undertook an evaluation of the performance and accuracy of the Dustbox 2.0 devices by co-locating them with the regulatory-standard London Air Quality Network (LAQN) monitor at New Cross Gate in Lewisham. We set up the monitors and mobile router with the help of the Environmental Health and Protection team at Lewisham Council. We undertook the co-location for a period of approximate two months to enable comparison of the Dustbox sensor output with a regulatory instrument. The site for the co-location study was strategically chosen so that the devices could be evaluated under varying environmental conditions and pollution levels of particulate matter 2.5, in an area nearby our ongoing installation of Dustbox 2.0 devices.
In the co-location study, our aim is to evaluate the accuracy of the sensors and to ensure that the Dustbox 2.0 sensors are able to capture sudden variations in pollution concentration from traffic and other emissions sources. We compared the 24-hour mean values of PM2.5 levels, and found encouraging results. The Dustbox 2.0 recorded variations and patterns similar to those captured by the LAQN monitor, as demonstrated in the line graph above. We performed statistical analysis on the dataset and found that the correlation (statistical relationship between values recorded by LAQN monitor and Dustbox) was 0.95, where values closer to +1 indicate higher accuracy and a positive relationship between the variables. Together with our pre-installation co-location and calibration captured in this earlier post we have established that the Dustbox 2.0 has a very high level of accuracy and performance for capturing PM2.5 in the London environment. Stay tuned for our AirKit Data Stories that will outline pollution sources we have identified during early spring to summer 2020.