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TITLE: A Portrait of Air Quality in the San Joaquin Valley

AUTHORS: Louise Wells Bedsworth

PAGES: 58      DATE: April 2003

ABSTRACT: This paper analyzes temporal and spatial trends in ozone air quality in the San Joaquin Valley. Trends in population growth, vehicle population, and vehicle use show that the pressures associated with population growth will continue to be a challenge for air quality improvement in the San Joaquin Valley. Recent downward trends in the number of days above the federal one hour ozone standard appear to be slowing down, and no significant trend exists in the number of days above the new federal 8-hour ozone standard. Large emission reductions have been achieved for both reactive organic gases (ROG) and oxides of nitrogen (NOx). The reductions achieved from stationary sources of ROG have contributed to area sources such as pesticides, fertilizers, and consumer products becoming an even more important contribution to the overall emission inventory. Reductions in the NOx emission inventory have not been as large as for ROG, and the distribution of sources has not changed significantly. Jurisdictional responsibility achieving air quality standards are split between all three levels of government - local, state, and federal. Spatial analysis shows that close to 80 percent of the Valley population lives within ten miles of an ozone air-quality monitor.

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