THE LONG LIFETIME OF THE DISPERSION METHODS OF PASQUILL IN US REGULATORY AIR MODELING

The suggestions of Pasquill as set forth in his landmark 1961 Meteorol ogical Magazine paper are briefly reviewed. These methods are viewed f rom the perspective of the requirements placed upon air agencies after the passage of the Clean Air Act in 1970. Pasquill's clarification of the use of his methods in a technical report for the Environmental Pr otection Agency (EPA) is discussed in relation to the incorporation of these methods into numerous air quality dispersion models. The shifts in the problem areas faced by the EPA and the relation of these to th e methods of Pasquill are discussed. Reasons are suggested for the lon g persistence of the Pasquill methods in the models used to address U. S. EPA regulations. Current trends in the incorporation of newer techn iques into regulatory modeling and their relation to the methods of Pa squill are briefly stated.