Search Results

Motor vehicle emissions have been determined to constitute a public health hazard, especially in the U.S. metropolitan areas. Under amendments to the Clean Air Act, the U.S. Congress has directed that national ambient air health standards must be met by specified dates. All reasonable control measures including vehicular emission inspection programs should be implemented in those areas not able to meet minimum public health ambient air levels. This potentially affects metropolitan areas in 40 states. This paper describes the implementation of an emission inspection program in the Portland, Oregon, metropolitan area, the effects of that program on the emissions from the area's motor vehicles, and the effect on ambient air quality.

The results obtained from the underhood inspection portion of the Oregon motor vehicle emission inspection/maintenance (I/M) program are reported. The underhood inspection for tampered or missing emission control equipment is an important element of Oregon's I/M program. The rate of emission control equipment disconnections are contrasted with federal survey results. These summaries indicate that this type of inspection shows reduced vehicular emission control tampering when compared to nationwide averages. This indicates that inspecting for onboard emission control equipment is an effective technique and contributes in achieving the goal of clean air.