Part I. Definition of Key Issues

Use of frequency distributions of potential ozone in evaluating oxidant controls

“…The problem of oxidants is more complex than is represented by the simple criterion of the ozone formed in 1-day irradiations (6), and the dependence of oxidants other than ozone on precursor concentrations has yet to be quantified for the range of precursor concentrations encountered in the airshed. Pitts (7) summarized a number of factors that make the reduction of emissions of NO, appear important in terms of the following observations: (a) although NO, emissions decrease ozone levels in the immediate area, they seem to raise ozone levels in areas downwind; (b) control of NO, reduces ambient levels of toxic NO2; (c) reduction of NO, emissions will lower ambient levels of secondary nitrate aerosols; (d) NO, is changed into many compounds such as PAN.…”

“…In Australia, control of NMHC only has been proposed (3,4), as has control of both NMHC and NOx (5). Many of the key issues that require resolution before the optimum control strategy can be de-veloped have been reviewed by Dimitriades and Altshuller (6) and Pitts (7). A recent analysis of isopleth diagrams that relate ozone formation to NMHC and NOx concentrations has led to a renewal of the proposal that control of NMHC emissions is the optimum strategy for control of photochemical oxidants (8).…”