Abstract

In heavy loaded traffic situations, large negative NO2 measurement data are regularly encountered. This is directly due to the technical construction of the employed standard Philips PW9762 nitrogen-oxide monitor. Upon presentation of the cumulative frequency distribution, the higher percentile values will be overestimated consequently ; particularly 10 and 15% for the 95 and 98-percentile one respectively. The use of 3-hourly floating averages, instead of the customary hourly ones enables a realistic estimate of these higher NO2- percentiles. Appropriate adaption of the shape of the sample delay volume enables the proper establishment of NO2, even in the afore-mentioned traffic situations.