“…States signing the MOU were com-mitted to developing and adopting regulations that would reduce region-wide NO x emissions in 1999 and further reduce emissions in 2003 [21]. 4 In September 1998, in effort to mitigate the regional transport of ground-level ozone in the eastern half of the United States, the EPA finalized a rule, known as the NO x SIP call, that required 22 states and the District of Columbia to submit state implementation plans (SIPs) to reduce NO x emissions [22]. These states are: Alabama, Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Kentucky, Maryland, Massachusetts, Michigan, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia.…”