Low-cost NO2 measurements at an urban high traffic site

A network of low-cost air quality sensors for monitoring NO2- and O3-concentrations has been installed at an urban high traffic site in the city of Munich (Bavaria, South Germany). NO2-measurements conducted over a period of several seasons are used to analyse the effectiveness of novel air filtering systems that have been installed alongside the street section.Estimates of hourly mean NO2-concentrations at the network sites are determined by applying several calibration methods (linear and non-linear models) that were fitted, validated and compared based on data gathered during two periods where all sensors were co-located at an on site official reference station.Resulting NO2-estimates at the low-cost network sites are further analysed with respect to spatiotemporal variations in NO2-concentrations. Thereby the effects of local scale variations in the urban environment, varying traffic loads, changing synoptic weather types and different operating conditions of the air filtering systems are considered.The contribution presents and discusses different approaches for the calibration of the low-cost NO2 measurements and shows preliminary results of the analyses of spatiotemporal NO2 variations in a high traffic urban environment under special consideration of the effectiveness of novel air filtering systems.