2014-069 - Final Environmental Impact Report No. 2014-01

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HARBOR BLVD. MIXED USE TRANSIT CORRIDOR PLAN FINAL FIR CITY OF SANTA ANA 5. Environmental Analysis AIR QUALITY Localized Significance Thresholds SCAQMD developed LSTs for emissions of NO2, CO, PM10, and PM25 generated at the project site (offsite mobile- source emissions are not included in the LST analysis). LSTs represent the maximum emissions at a project site that are not expected to cause or contribute to an exceedance of the most stringent federal or state AAQS. IST analysis is applicable for all projects of five acres and less. LSTs are based on the ambient concentrations of that pollutant within the project SRA and the distance to the nearest sensitive receptor compared to the most stringent AAQS. Thresholds are based on the California AAQS, which are the most stringent AAQS established to provide a margin of safety in the protection of the public health and welfare. They are designed to protect sensitive receptors most susceptible to further respiratory distress, such as asthmatics, the elderly, very young children, people already weakened by other disease or illness, and persons engaged in strenuous work or exercise. AAQS from which the LSTs are based are shown in Table 5.2 -6. Table 5.2 -6 SCAQMD Localized Significance Thresholds Air Pollutant Relevant AAQS Concentration 1 -Hour CO Standard (CAAQS) 20 ppm 8-Hour CO Standard (CAAQS) 9.0 ppm 1 -Hour NO2 Standard (CAAQS) 0.18 ppm 24-Hour PM10 Standard — Construction (SCAQMD)l 10.4 Ng /m3 24-Hour PM2.5 Standard — Construction (SCAQMD)l 10.4 Ng /m3 24-Hour PM10 Standard — Operation (SCAQMD)l 2.5 Ng/m3 24-Hour PM2.5 Standard — Operation (SCAQMD)l 2.5 Ng/m3 ppm — parts per million; Ng/m3 — micrograms per cubic meter ' Threshold is based on SCAQMD Rule 403. Since the SoCAB is in nonattainment for PM10 and PMzs, the threshold is established as an allowable change in concentration. Therefore, background concentration is irrelevant. Health Risk Analysis Whenever a project would require use of chemical compounds that have been identified in SCAQMD Rule 1401, placed on CARB's air toxins list pursuant to Assembly Bill 1807 (AB 1807), Air Contaminant Identification and Control Act (1983), or placed on the EPAs National Emissions Standards for Hazardous Air Pollutants, a health risk assessment (TIRO) is required by the SCAQMD. Table 5.2 -7 lists the SCAQMD's TAC incremental risk thresholds for operation of a project Residential, commercial., and office uses do not use substantial quantities of TACs, and these thresholds are typically applied for new industrial projects. Although not officially adopted by SCAQMD, these thresholds are also commonly used to determine air quality land use compatibility of a project with major sources of TACs within 1,000 feet of a proposed project. Table 5.2 -7 SCAQMD Toxic Air Contaminants Incremental Risk Thresholds Maximum Individual Cancer Risk I ? 10 in 1 million Hazard Index (proiect increment) I ? 1.0 Source: SCAQMD 2011. Page 5.2 -14 PlaceWorkr