TERI Administrator Note (January 2009): Project funded as NCHRP 25-25-59 in 2009

The effect of control strategies on both PM and ozone is important because many areas of the country designated as nonattainment for PM_2.5 are also ozone nonattainment or maintenance areas. This is because in many locations (particularly in the Eastern half of the United States) similar meteorological conditions conducive to high ozone formation also lead to high levels of PM_2.5. As a result, State and local decisionmakers need to understand the implications of control strategies on both PM_2.5 and ozone as well as the implications on air toxics and greenhouse gases.

Some control strategies may be beneficial in reducing both PM and ozone pollution. Since the ozone precursors, VOC and NO_X, are also precursors for secondary PM, ozone controls may already be working to reduce secondary PM formation. On the other hand, some ozone control strategies may result in increased PM as well as other effects on air toxics and greenhouse gases. For example, an increase in transit bus service provision could increase PM emissions since diesel buses have high PM emission rates compared to other classes of vehicles. This would in addition increase air toxic emissions since diesel is considered a significant air toxic. Conversely, carbon dioxide would decrease as the transit bus service produces significantly less carbon dioxide than gasoline fueled vehicles.

This project involves modeling the impacts of transportation control strategies on both PM and ozone as well as their impact on air toxics and greenhouse gases using emission factor models and urban air shed models.