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California Air Resources Board

Annual Toxics Summary
ARB's ADAM Air Quality Database
Richmond-13th Street
Methylene Chloride
parts per billion
Year Months
Present
Minimum Median Mean 90th
Percentile
Maximum Standard
Deviation
Number of
Observations
Detection
Limit
Estimated
Risk
2002
            0    
2001
            0    
2000
            0    
1999
            0    
1998
            0    
1997
0.5       0.5 0.00 9 1.0  
1996
0.5 0.5 0.65 1.1 2.0 0.35 31 1.0 2
1995
0.5 0.5 0.54 0.5 1.4 0.19 30 1.0 2
1994
0.5 0.5 0.50 0.5 0.5 0.00 31 1.0 2
1993
0.5 0.5 0.67 1.0 2.8 0.46 30 1.0 2
1992
0.5 0.5 0.54 0.5 2.1 0.30 29 1.0 2
1991
0.5 0.5 0.62 0.5 2.4 0.39 27 1.0 2
1990
0.5 0.5   1.4 5.4 1.16 28 1.0  
1989
0.5 0.5   1.1 1.6 0.35 24 1.0  
Notes Values below the Limit of Detection (LoD) assumed to be ½ LoD.
Means and risks shown only for years with data in all 12 months.
Risks shown only for those substances with unit risk factors.