Emission cutpoints are used to classify vehicles as "gross polluters" in inspection and maintenance (I/M) testing in the United States. In this study, we use recent data from California I/M tests to examine how sensitive populations of "gross polluters" change as cutpoints are modified. Using statistical analyses of emissions test data, we identify a variety of scenarios that have the potential for efficiently removing a significant portion of the exhibited emissions while minimizing the number of vehicles that are classified as "gross polluters" and required to undergo costly repairs. For each scenario, we compute the resulting vehicle populations and impact on emissions. The conclusions of the research provide support for previous findings that suggest that: 1) a "gross polluting" vehicle for one pollutant, such as carbon monoxide (CO), may not necessarily be a "gross polluter" for another pollutant, such as oxides of nitrogen (NOx) and 2) each of the existing required I/M tests yield similar results and it may not be efficient to use both tests in the identification of gross polluters. For the covering abstract see ITRD E128680.
Samenvatting