Effects of averaging time on predicted gas concentrations

The potential consequences of a particular gaseous emission usually relate to a specific averaging time. However, the averaging time associated with g as monitoring data in the region of a discharge may differ from the averagi ng time implicit in a model employed to predict the concentration resulting from that emission. Tables of factors exist for taking account of such dif ferences and recent models include expressions that convert predicted value s to the appropriate averaging time. This paper presents the results of a s tudy of the factors used in these regulatory tables, and makes comparisons with the equivalent factors deduced from runs with a gas dispersion model a nd sonic anemometer observations.