Based on a spatio-temporal pattern and transport considerations, some general control approaches appear to have high leverage, i.e. substantial reduction in the ozone-induced risk with modest effort. A measure of the overall impact, i.e. risk could be the excess ozone concentration weighed by the population density. Geographically, the regions that are located in the center of OTAG tend to impact on downwind areas regardless in which direction the wind blows. On the other hand, urban ozone concentrations have high impacts because of high population density. The reduction of area sources would appear suitable for intermittent, high-leverage episodic controls. High-leverage ozone control could also be achieved if the ozone control measures would also reduce the emissions of other pollutants, e.g. SOx and NOx from point sources would reduce both ozone and fine particles. Geographic - reductions where the overall source impact on risk (ppb x population) is the highest Temporal reductions during episodes Emissions that can be co-controlled with other pollutants, e.g. PM2.5