FIGURE 4 The (arbitrary) sensor numbers are provided, the number of used data points and the average concentrations measured by the bikes. The final column provides the average concentration measured by the official locations during the same hours that the sensor provided data. All concentrations in microgram per cubic meter. FIGURE 5 AND 6 The data for these figures are provided in sets of columns, with the hourly data for Kardinaal de Jonge, Breukelen, Griftpark and Cabauw. The first column has the raw sensor data and the second the official data. Sensor data consist of the average of the co-located sensor (not on Griftpark) and all sensors that pass nearby in an hour. The last column is for figur e 6 and provides the calibrated sensor data for Kardinaal de Jonge using the Leave Station Out method described in the text. All concentrations in microgram per cubic meter. FIGURE 7 The data for three typical bike trips are provided in the figure in three columns each. First the number of seconds in the trip, the measured data and the estimated background for the trip. All concentrations in microgram per cubic meter. FIGURE 8 The data are provided as columns "Hour" and "Count bikes" for figure 8a and "Month" and "Count bikes" for figure 8b. FIGURE 9 The data are provided as columns "Hour" and "Concentration bikes" and "Concentration Griftpark". All concentrations in microgram per cubic meter. FIGURE 10 The data are provides as three columns, concentration, number of bike trips with this average total concentration, average concentration at official location Griftpark at the same hours as the bike measurements. All concentrations in microgram per cubic meter. FIGURE 11 The data are provides as five columns. First the concentration-contribution, followed by number of bike trips with this average concentration-contributions, assuming backgrounds derived from the 05, 10 and 15 percentile (see text). The last column is derived assuming a background derived from the 10 percentile with the additional requirement of having at least 50 measurements in the bike trip. FIGURES 12 and 13 Figures 12 and 13 are different views of the data in the file "Figure_12_13_data.csv". These data are in WKT format with columns "geometry" and "pm25road". The geometry CRS is EPSG:28992 (Amersfoort / RD New) and the pm25road are in microgram per cubic meter. The figures were created using QGIS 3.16. The color scale was determined using the "Equal Count (Quantile)" classification option of QGIS. The full style is provided in "Figure_12_13_style.qml".