The air pollution potential of the Upper Santa Clara River Valley

The impact of urbanization within the confines of the Upper Santa Clara River Valley (USCRV) on the air quality of that region, and the extent to which metropolitan Los Angeles air quality affects that of the USCRV has not been previously investigated. Emissions of such contaminants as oxides of nitrogen, sulfur dioxide, carbon monoxide, and hydrocarbons, into the atmosphere of the USCRV are notably small by volume in comparison with those emissions attributed to its neighbor the Los Angeles Basin. Nitrogen dioxide and hydrocarbons are the two primary contaminants known to contribute significantly to the accumulation of ozone in the photochemical process. An examination of recorded data, measuring each of these contaminants and the recorded values for ozone found in the USCRV, indicates low concentrations of primary contaminants. Yet significant episodes of air pollution in terms of ozone occur in the USCRV; the California standard for ozone (0.10 ppm/hr.) was exceeded on an average of 149 days per year there in the 1970-1973 period. Clearly the low concentrations of primary contaminants cannot account for the high concentrations of ozone monitored. This implies that ozone comes from a source other than the USCRV. This study, through analysis of air quality data and atmospheric transport patterns, shows that the USCRV air basin is a prime receptor area for Los Angeles Basin atmospheric contaminants and that its air quality suffers accordingly.