EXHIBIT 4-2_55A_BRISTOL WIDENING TECHNICAL STUDIES

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IAmbient Air Quality The South Coast Air Quality Management District (SCAQMD) main- tains ambient air quality monitoring stations at numerous loca- tions, the closest of which is in Anaheim. Ambient air quality data from this station is given in terms of state and federal standards which were adopted to protect public health with a margin of safety ( see pages 2 and 3 of the Appendix) . In addi- tion, California has adopted episode criteria for ozone, carbon monoxide, sulfur dioxide, and sulfates in combination with ozone. Episode criteria represent short -term exposures at concentrations that threaten public health (see page 4 of the Appendix). The South Coast Air Basin has been designated a nonattainment area because of violations of the national ambient air quality standards for carbon monoxide, ozone, nitrogen dioxide and total suspended particulates. Air quality trends which have developed at the Anaheim air quality monitoring station between 1983 and 1985 are detailed on page 5 of the Appendix and summarized below. It can be seen that sulfur dioxide, sulfate and lead have not equalled or exceeded the relevant state or federal standards. Oxidant (ozone), particulates, carbon monoxide, and nitrogen dioxide have exceeded the ambient air quality standards. 1 Of all the pollutants monitored, ozone equals or exceeds the state and federal standards most often. The California one -hour ozone standard (0.10 ppm) was equalled or exceeded on 19 percent of the days monitored in Anaheim. The less stringent federal one -hour standard (0.12 ppm) was exceeded on 10 percent of the days monitored. The maximum one hour concentration measured was 0.30 ppm. Nineteen Stage One ozone episodes were called at the Anaheim station, 10 in 1983, 5 in 1984, and 4 in 1985. There were no Stage Two episodes declared for ozone. Suspended particulates exceeded the California 24 -hour standard of 100 micrograms per cubic meter on 4 percent of the days moni- tored at the Anaheim station during 1983 and 1984. Suspended particulates were not monitored at this station during 1985. The less stringent federal 24 -boor standard of 260 micrograms per cubic meter was not exceeded. The highest 24 -hour concentration measured was 215 micrograms per cubic meter (more than twice the state standard). The state and federal 8 -hour carbon monoxide standard (9 ppm) was equalled or exceeded on 1 percent of the days monitored at the Anaheim station. The l -hour state standard (20 ppm) and federal standard (35 ppm) were not exceeded on the days monitored at this station. The maximum 1 -hour Co concentration measured at the Anaheim station was 19 ppm (compared to the 20 ppm state stan- dard). t 1 3 -2