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32 <br />the interstate incident management program. As more experience is gained in other activities, <br />they may be reflected in future conformity analyses. FHWA Region IV's Off-Model Air Quality <br />Analysis: A Compendium of Practice provided guidance on estimating these emissions effects. <br />Appendix H includes the calculations for this off-model analysis in Durham and Wake Counties. <br />4.5 Emissions Comuarison Tests by Location and Pollutant <br />USEPA originally declared Durham County, Wake County and Dutchville Township in Granville <br />County non-attainment under the 1-hour standazd for ozone (03) and Durham County and Wake <br />County non-attainment for Cazbon Monoxide (CO) on November 15, 1990. Durham County, <br />Wake County and Dutchville Township were redesignated by USEPA to attainment with a <br />maintenance plan for ozone on June 17, 1994 and Durham County and Wake County were <br />redesignated by USEPA to attainment with a maintenance plan for CO on September 18, 1995. <br />In 1997 the NAAQS for ozone was reviewed and revised to reflect improved scientific <br />understanding of the health impacts of this pollutant. When the standazd was revised in 1997, an <br />eight-hour ozone standard was established. The USEPA designated the entire Triangle area as a <br />"basic" non-attainment area for eight-hour ozone with an effective date of June 15, 2004. The <br />Triangle Area was subsequently redesignated to a Maintenance Area for eight-hour ozone on <br />December 26, 2007. <br />The current maintenance designation covers the following geographic areas: <br />• Durham County <br />• Wake County <br />• Orange County <br />• Johnston County ' <br />• Franklin County <br />• Granville County <br />• Person County <br />• Baldwin, Center, New Hope and Williams Townships in Chatham County <br />Both volatile organic compounds (VOCs) and oxides of nitrogen (NO,~ aze precursors of ozone. In <br />the most recently approved maintenance plans for ozone for the areas listed above, the North <br />Carolina Department of Environment and Natural Resources (DENR) prepazed emissions budgets <br />for only NOx, as VOC was deemed insignificant. USEPA approved the most recent emissions <br />budgets on December 26, 2007 with an effective date of the same day. The USEPA approval and <br />promulgation rulings for CO and ozone containing the budgets aze in Appendices A and B. <br />Four organizations are responsible for conformity determinations; each must make a conformity <br />determination for its respective area in order for all of the azeas to be designated in conformity: <br />• the Capital Area MPO within the CAMPO metropolitan area boundary -currently all of <br />Wake County, and portions of Franklin, Granville and Johnston Counties. <br />• the DCHC MPO within its metropolitan azea boundary -all of Durham County and parts of <br />Orange and Chatham counties. <br />• the Burlington-Graham MPO within its portion of the metropolitan area boundary in western <br />Orange County. <br />24 <br />