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City of Santa Ana -Park View at Town and Country Manor <br />Draft EIR <br />and early morning periods of transition between day and nighttime flows. The region also <br />experiences periods of hot, dry winds from the desert, known as Santa Ana winds. If the Santa Ana <br />winds are strong, they can surpass the sea breeze, which blows from the ocean to the land, and cant' <br />the suspended dust and pollutants out to the ocean. If the winds are weak, they are opposed by the <br />sea breeze and cause stagnation, resulting in high pollution events. <br />Temperature inversions limit the vertical depth through which pollution can be mixed. Among the <br />most common temperature inversions in the basin, radiation inversions form on clear winter nights <br />when cold air off mountains sink to the valley floor while the air aloft over the valley remains warm. <br />These inversions, in conjunction with calm winds, trap pollutants near the source. Other types of <br />temperature inversions include marine, subsidence, and high - pressure inversions. <br />Summers are often periods of hazy visibility and occasionally unhealthful air, while air quality <br />impacts in the winter tend to be highly localized and can consist of odors from agricultural operations. <br />Local Air Quality <br />The local air quality can be evaluated by reviewing relevant air pollution concentrations near the <br />project area. For evaluation purposes, the SCAQMD has divided the basin into 36 Source Receptor <br />Areas within the South Coast Air Basin, operating monitoring stations in most of the areas. These <br />Source Receptor Areas are designated to provide a general representation of the local meteorological, <br />terrain, and air quality conditions within the particular geographical area. <br />The project site is within Source Receptor Area 17. The SCAQMD operates a measurement site <br />within Source Receptor Area 17 in Anaheim where concentration data are collected. This data along <br />with data collected from a monitoring station in a nearby Source Receptor Area were integrated to <br />form a "background" description of air quality in the project area. This latter monitoring station is <br />located in North Coastal Orange County (Source Receptor Area 18 - Costa Mesa), which monitors <br />sulfur dioxide. Table 4.2 -1 summarizes the monitoring data for the period 2006 to 2008, the most <br />recent three -year period of measurements available. <br />Table 4.2.1: Local Air Quality <br />it Pollutant, Averaging Time (Units) <br />2006 <br />2008 <br />Ozone <br />Maximum 1 Hour (ppm) <br />0.113 <br />0.127 <br />0.105 <br />Days > CAAQS (0.09 ppm) <br />6 <br />2 <br />1 <br />Maximum 8 Hour (ppm) <br />0.088 <br />0.099 <br />0.086 <br />Days > CAAQS (0.070 ppm) <br />5 <br />7 <br />10 <br />Days > NAAQS (0.075 ppm) <br />3 <br />1 <br />5 <br />Carbon Monoxide <br />Maximum 1 Hour (ppm)•• <br />5 <br />4 <br />ND <br />Days > CAAQS (20 ppm) <br />0 <br />0 <br />ND <br />Days > NAAQS (35 ppm) <br />0 <br />0 <br />ND <br />4.2 -2 <br />Michael Brandman <br />Associates <br />H\Cl t(PN- <br />JMb327b327W3MMVB270030 Sec 2AvQ ity.D <br />