TROPOSPHERIC OZONE - THE DEBATE OVER CONTROL STRATEGIES

It is commonly recognized that ozone is sensitive either to hydrocarbons or to NOx emission, depending on the chemistry at individual locations. It is often not recognized that ozone formation follows a natural progression as an air mass ages, in which the initial rate of ozone formation is sensitive to hydrocarbons, and the amount of ozone produced after all precursors have had time to react is sensitive to NOx. When placed in this context, the choice between hydrocarbon and NOx controls becomes a choice between a localized control strategy for an individual city and a strategy that emphasizes downwind impacts and regional and global transport. To the extent that ozone is viewed as an isolated problem of individual cities, it is likely that control strategies will overestimate the importance of hydrocarbon controls and underestimate the importance of NOx. -from Author