On March 22, 2007, EPA issued a final rule governing the review and handling of air quality monitoring data influenced by "exceptional events." 72 Fed. Reg. 13560. Exceptional events are defined to include events for which the normal planning and regulatory process established by the Clean Air Act (CAA) is not appropriate. In the final rule, EPA implements CAA Sections 319(b)(3)(B) and 107(d)(3) authority to exclude air quality monitoring data from regulatory determinations related to exceedances or violations of the National Ambient Air Quality Standards (NAAQS) and avoids designating an area as nonattainment, redesignating an area as nonattainment, or reclassifying an existing nonattainment area to a higher classification if a state adequately demonstrates that an exceptional event has caused an exceedance or violation of a NAAQS. EPA also requires states to take reasonable measures to mitigate the impacts of an exceptional event. The rule is effective May 21, 2007.