Editors' Summary: The 1977 Clean Air Act Amendments single out for harsh air pollution control measures those parts of the country whose air quality does not measure up to federal standards. Virtually every major city in the country was a nonattainment area for ozone, the regulatory surrogate for smog. The final deadline for cleaning up these areas expires next year and many cities still have too much smog. They are trying to implement difficult control measures such as automobile emission control inspection and maintenance programs, and face potentially severe sanctions when time runs out if Congress does not first amend the Act. Several states have tried to cut down the scope of this predicament by shrinking the boundaries of urban nonattainment areas, excluding counties that no longer violate the air quality standards. The Act provides mechanisms for making such changes and can be read to give the states absolute power to make such counties attainment areas. EPA has resisted the proposed changes for counties with significant emissions of ozone precursors that are transported into the nonattainment areas on the prevailing winds, at least where parts of the counties are within the urbanized areas. Two recent courts of appeals decisions have held that the Clean Air Act authorizes EPA to insist that such counties remain in the nonattainment areas to whose problems they contribute. The result is a modest, but significant victory for EPA in its efforts to maintain the vitality of the ozone nonattainment program.