ABSTRACT
This chapter presents a model that could serve as a basis for an a priori screening methodology and discusses the model’s applicability using some case studies. It addresses gas-phase air toxics, atmosphere-to-plant canopy pathway in general and atmosphere-to-individual leaf pathway specifically, and transport and fate of air toxics rather than biological effects on plants and animals. The chapter aims to identify a set of physiochemical parameters from which predictions can be offered with respect to the probability that a given compound will be transported from the atmosphere to the biosphere. Toluene is a common organic emission from many different industrial sources; it is listed as one of the air toxic compounds identified by the US Environmental Protection Agency in the new amendments to the Clean Air Act. The physiochemical and physiological factors governing the atmosphere-to-individual-leaf flux of gas-phase air toxics have been reasonably well characterized from a conceptual and first principles perspective.
