Chapter 2	"Maximum 24-Hour, 98th Percentile, and Annual PM2.5 Concentrations by Air Basin"					Table 2-15
AIR BASIN	2004 Maximum 24-Hr Concentration in micrograms/cubic meter		98th Percentile 24-Hr Conc. (ug/m3)**	2004 Average of Quarterly Means in micrograms/cubic meter**		
	State	National		State	National	
Great Basin Valleys Air Basin	81.0	81.0	Incomplete Data	Incomplete Data	Incomplete Data	
Lake County Air Basin	18.1	18.1	9.0	4.4	4.4	
Lake Tahoe Air Basin	23.2	20.0	Incomplete Data	Incomplete Data	Incomplete Data	
Mojave Desert Air Basin	34.0	34.0	20.0	10.8	10.8	
Mountain Counties Air Basin	148.4	44.0	33.0	11.7	11.7	
North Central Coast Air Basin	22.6	22.6	15.5	6.8	7.0	
North Coast Air Basin	25.6	25.6	23.1	7.0	8.2	
Northeast Plateau Air Basin	Incomplete Data	Incomplete Data	Incomplete Data	Incomplete Data	Incomplete Data	
Sacramento Valley Air Basin	76.3	65.0	54.0	16.5	15.1	
Salton Sea Air Basin	76.0	74.2	31.9	16.1	11.8	
San Diego Air Basin	67.3	67.3	37.4	14.1	14.1	
San Francisco Bay Area Air Basin	73.7	73.7	39.8	11.6	11.6	
San Joaquin Valley Air Basin	77.0	71.0	54.0	18.2	18.9	
South Central Coast Air Basin	91.9	41.2	36.7	12.5	12.6
South Coast Air Basin	93.8	93.8	72.4	16.6	22.1

"The table lists the highest value for each statistic. Within an air basin, the highest value for each statistic may reflect a different site. In addition, the State and national requirements for data completeness are different. This may"					
"result in marked differences between the State and national values for the same statistic (e.g., maximum annual averages for the Salton Sea and South Coast air basins)."					
"* These statistics and determination of their validity are calculated according to the methods specified in 40 CFR Part 50, Appendix N. Validity is based on the number of measurements available per quarter and therefore, depends on data completeness."					
"Both the 98th percentile concentration and the average of quarters concentration relate to the national PM2.5 standards, while only the average of quarters concentration relates to the State PM2.5 standard."					
"24-hour data - The table may include data from extreme, exceptional, or unusual concentration events: however, there is a mechanism in place to review for these types of events during the area designation process."					
"Annual average data - Extreme, exceptional, or unusual concentration events do not generally significantly influence the annual average. However, their exclusion can be considered on a case-by-case basis."