Comments on Evidence of precursor emission changes
Bullet #2: AQA should examine the regional variability of this effect. It may be more evident in some urban areas (e.g., OTR) than others. It should be noted that the change in emissions involves both timing and amount, neither of which has been well quantified.
At the St. Louis meeting, Till Stokenius showed an interesting plot of historical NOx and VOC emissions trends - disaggregated by EPA region. As I recall, certain regions had experienced relatively large reductions in both VOC and NOx emissions. The regions with largest reductions in both precursor species are also regions where largest concurrent improvements in Ozone concentrations have been observed (as in Howard Feldman's report on OTR trends). Some comments linking the emissions and ozone regional trends would be an appropriate thing to include in this section.
