The I/M Success Story: Where Do We Go from Here?

Inspection and maintenance (I/M) programs have increased substantially in response to the Clean Air Act Amendments of 1977. Experience has indicated that they can achieve significant reductions in both hydrocarbons and carbon monoxide. This paper reviews the experience with existing programs in the US and suggests items which should be improved to increase overall I/M benefits. In addition, it explores the potential expansion of I/M to reduce NOx and diesel particulate emissions.