Is there evidence that precursor emission changes cause ozone concentration changes?

There is empirical evidence that anthropogenic emission changes do cause changes in ambient ozone concentrations. The weekly cycle of emissions differs from the diurnal and seasonal cycles in that it is exclusively due to man's activities. Hence, a weekly ozone cycle must be exclusively due to anthropogenic emission changes. There is indeed a weekly ozone cycle; ozone data show that throughout the OTAG domain, on Sundays, the 1-hour 120 ppb exceedances are reduced by factor of 3 compared to Friday exceedances. This reduction is most pronounced in urban areas, while in the central portion of the OTAG domain, the weekly ozone cycle is virtually nonexistent. Hence, any control scenario that simulates the weekday-weekend emission changes would be effective in reducing the 1-hour 120 ppb exceedances. It should be noted that the 8-hour 80ppb exceedances show less weekly fluctuations, indicating that such a control scenario would be less effective in reducing nonattainment with respect to the new standard.

(a) (b)
Figure 1. a) Map of exceedances on Fridays. b) Map of exceedances on Sundays.