Pursuant to a congressional request, GAO evaluated and commented on the Environmental Protection Agency's (EPA) responses to congressional questions on its vehicle emissions inspection and maintenance (I/M) program, to: (1) determine whether the responses adequately addressed the 58 specific questions raised; and (2) test, to the extent possible, the adequacy and reasonableness of the responses.

GAO found that some of the conditions identified in an earlier report continued to exist and it identified some new concerns, including that: (1) 12 of the 44 areas of the country required to implement the I/M program did not have EPA-approved state implementation plans showing how they would attain air quality standards by 1987; (2) 26 areas not initially required to implement an I/M program had inadequate state implementation plans; (3) although measurable levels of carbon monoxide have declined, ozone levels have increased and continue to be a pervasive pollution problem; (4) 21 to 56 percent of 1981 and later model-year vehicles could be expected to have serious malfunctions in emission control systems; (5) EPA approval of I/M programs using window stickers rather than annual vehicle re-registrations weakened program effectiveness; (6) many programs continued to experience serious problems, such as lack of quality assurance in testing equipment, and inspection and data reporting errors; (7) some states were not cooperating with EPA to implement changes in their I/M programs to make them more effective; (8) although EPA can use sanctions against any state failing to implement a program, it has only used them sparingly; (9) no follow-up or monitoring of problems have been identified in audits; and (10) the cost to repair new-technology vehicles not passing an I/M test may be substantially greater than existing repair cost limits, which could make vehicles eligible for program waiver and exclude them from further tests.