California Air Resources Board California Map with County Boundaries
Ozone Data Summaries (1980-1998)
Contra Costa County
Year Number of Days Standard Exceeded Ozone Concentrations in ppm
1 hour 8 hour
State
1hr
Federal
1hr
Federal
8hr
Max
1hr
3 Year
4th High*
EPDC*
Max
8hr
3 Year Avg
4th High*
1998 16 2 8 0.15 0.12 0.126 0.109 0.083
1997 4 0 0 0.11 0.13 0.124 0.081 0.083
1996 15 1 5 0.14 0.13 0.125 0.100 0.085
1995 12 4 6 0.15 0.13 0.121 0.114 0.081
1994 6 0 2 0.12 0.12 0.110 0.097 0.079
1993 10 2 2 0.13 0.11 0.111 0.096 0.079
1992 7 0 2 0.11 0.11 0.112 0.092 0.081
1991 5 0 2 0.11 0.11 0.113 0.088 0.083
1990 7 0 5 0.12 0.11 0.115 0.105 0.086
1989 12 0 7 0.11 0.13 0.129 0.097 0.088
1988 12 1 5 0.14 0.13 0.128 0.095 0.086
1987 22 3 15 0.15 0.13 0.129 0.105 0.088
1986 9 0 4 0.12 0.13 0.129 0.092 0.088
1985 15 2 5 0.15 0.13 0.140 0.103 0.088
1984 18 3 11 0.16 0.13 0.143 0.116 0.091
1983 17 7 9 0.15 0.13 0.136 0.101 0.089
1982 15 1 9 0.13 0.13 0.134 0.108 0.091
1981 20 2 8 0.13 0.13 0.121 0.097 0.091
1980 15 3 8 0.14 0.15 0.138 0.123 0.097
* The 3 year 4th high, 3 year average 4th high, and Expected Peak Day Concentration (EPDC) are calculated based on data for 3 successive years, listed by the last year of the three year period.  The EPDC represents the ozone concentration expected to occur once per year.
   

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This page last revised on March 26, 1999

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