Application of linear regressions to the comparison of analytical procedures for the determination of SO2 in ambient air

Three commonly used analytical methods for the determination of SO2 in ambient air were compared during 10 months at six different sites. The acidimetric method, used in the Sulfur-Black Smoke network, and the FPD method, used in the Belgian Automatic Network for Air Pollution, were compared with the TCM reference method. Several regression methods were used to calculate the relationships between the daily averages obtained by the three measuring techniques. Knowledge of the relative importance of the errors on the different sets of data was a determining factor for the selection of the most suitable regression method. The results show good agreement between the three methods during the field-test period.