Development of Low-Cost Air Quality Stations for Next Generation Monitoring Networks: Calibration and Validation of PM2.5 and PM10 Sensors

A low-cost air quality station has been developed for real-time monitoring of mainatmospheric pollutants. Sensors for CO, CO2, NO2, O3, VOC, PM2.5 and PM10 were integratedon an Arduino Shield compatible board. As concerns PM2.5 and PM10 sensors, the station underwenta laboratory calibration and later a field validation. Laboratory calibration has been carried out atthe headquarters of CNR-IBIMET in Florence (Italy) against a TSI DustTrak reference instrument.A MATLAB procedure, implementing advanced mathematical techniques to detect possible complexnon-linear relationships between sensor signals and reference data, has been developed andimplemented to accomplish the laboratory calibration. Field validation has been performed acrossa full "heating season" (1 November 2016 to 15 April 2017) by co-locating the station at a roadsite in Florence where an official fixed air quality station was in operation. Both calibration andvalidation processes returned fine scores, in most cases better than those achieved for similar systemsin the literature. During field validation, in particular, for PM2.5 and PM10 mean biases of 0.036 and0.598 ?g/m3, RMSE of 4.056 and 6.084 ?g/m3, and R2 of 0.909 and 0.957 were achieved, respectively.Robustness of the developed station, seamless deployed through a five and a half month outdoorcampaign without registering sensor failures or drifts, is a further key point.