California Air Resources Board California Map with County Boundaries
Ozone Data Summaries (1980-1998)
San Mateo 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 0 0 0 0.07 0.09 0.078 0.053 0.053
1997 0 0 0 0.09 0.10 0.100 0.073 0.062
1996 1 0 0 0.10 0.10 0.099 0.067 0.061
1995 5 1 2 0.14 0.10 0.092 0.099 0.058
1994 0 0 0 0.08 0.08 0.076 0.066 0.049
1993 1 0 0 0.10 0.08 0.076 0.076 0.050
1992 0 0 0 0.09 0.07 0.071 0.065 0.049
1991 0 0 0 0.08 0.08 0.078 0.056 0.053
1990 0 0 0 0.08 0.09 0.089 0.050 0.058
1989 1 0 0 0.10 0.10 0.098 0.072 0.065
1988 2 0 0 0.10 0.10 0.097 0.076 0.060
1987 2 0 0 0.12 0.11 0.099 0.074 0.060
1986 1 0 0 0.10 0.11 0.104 0.071 0.061
1985 5 1 0 0.13 0.11 0.121 0.077 0.068
1984 9 0 0 0.11 0.11 0.116 0.080 0.063
1983 8 2 2 0.17 0.11 0.110 0.088 0.058
1982 1 0 0 0.10 0.12 0.102 0.060 0.059
1981 2 1 1 0.13 0.13 0.107 0.087 0.064
1980 4 2 2 0.15 0.12 0.113 0.102 0.062
* 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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