Air quality in the United States has been improving in recent years as a result of both regulations and voluntary measures. To help the U.S. meet National Ambient Air Quality Standards (NAAQS), the EPA has established attainment/non-attainment zones for each state throughout the United States. When a zone is designated as non-attainment for any criteria pollutant, the affected state must establish a state implementation plan. The state implementation plan regulates emissions of air pollutants so that the non-attainment zones can achieve the National Ambient Air Quality Standards. Although the majority of the US is classified as "ozone attainment," there are many “ozone non-attainment” areas and several cities have had persistent ozone problems for many years. More information about non-attainment zones can be obtained at the EPA Website.
The U.S. EPA recently released figures to show that VOC emissions from non-biogenic sources in the U.S. have declined by 52% in the 16 year period ranging from 1980 to 2006. A closer examination of this information reveals, however, that the majority of these gains were made in the early years of the program. The chart below shows that the reduction of VOC emissions has tailed off in recent years and that more moderate mass reduction can be expected in the future.
This shrinking pool of VOCs available for ozone control has important implications for the development of control options. Many ozone nonattainment areas in the East and Southwest have projected large shortfalls in their VOC reduction goals. This has necessitated far stricter emission limits on solvent VOCs to compensate for increases associated with population growth. These new restrictions highlight the need for innovative ways of thinking about the relationship between VOC use and ozone formation like the implementation of reactivity-based controls.
Learn more about reactivity-based controls