Environmental Services Program
St. Charles Rock Road, St. Ann - Breckenridge Hills
Site Operator: St. Louis County Department of Health, Air Pollution Monitoring Program
Pollutants Monitored: Ozone (O3), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), Carbon Monoxide (CO)
Ozone (O3)
Updated: Only historical data shown below. Instrument has been discontinued.
National Ambient Air Monitoring Standard:
Eight-hour Standard
The three-year average of the fourth highest daily maximum eight-hour
average must not be greater than .08 ppm (parts per million). Data reported
in three decimal places must be rounded to two decimal places.
One-hour Standard 1970 to 1997-no longer applies to any area
in Missouri.
A one-hour average of 0.12 ppm (parts per million).
Exceedances allowed without a violation being recorded:
The term exceedance does not apply to the eight-hour standard. The three-year
average is used to determine designation of attainment or non-attainment.
Disclaimer: Yearly and quarterly data shown below has been subject to data review and validation procedures by the reporting agency. Monthly data and data shown graphically is raw, unreviewed and unvalidated data.
| Year | Number of Days Over Standard |
Maximum 1-Hour Average |
Maximum 8-Hour Average |
Fourth Maximum 8-Hour Average |
|---|---|---|---|---|
| 1993 | 0 | .109 | not available | not available |
| 1994 | 4 | .149 | not available | not available |
| 1995 | 1 | .131 | not available | not available |
| 1996 | 0 | .109 | not available | not available |
| 1997 | 0 | .111 | not available | not available |
| 1998 | 1 | .146 | not available | not available |
| 1999 | 1 | .139 | not available | not available |
| 2000 | 0 | .122 | not available | not available |
| 2001(Site moved to Breckenridge Hills) | ||||
| 2001 | 0 | .090 | not available | not available |
| 2002 | 11 | .118 | .103 | .093 |
| 2003 | 5 | .134 | .106 | .088 |
| 2004 | 0 | .089 | .072 | .069 |
| 2005(Site Shut Down) | ||||
Nitrogen Dioxide (NO2)
Updated: Only historical data shown below. Instrument has been discontinued.
National Ambient Air Monitoring Standard: An annual average of 0.053 ppm (parts per million).
Exceedances allowed without a violation being recorded: None.
Disclaimer: Yearly and quarterly data shown below has been subject to data review and validation procedures by the reporting agency. Monthly data and data shown graphically is raw, unreviewed and unvalidated data.
| Year | Number of Exceedances |
Annual Average |
Maximum 1-Hour Average |
|---|---|---|---|
| 1993 | 0 | .018 | .079 |
| 1994 | 0 | .020 | .085 |
| 1995 | 0 | .022 | .103 |
| 1996 | 0 | .020 | .077 |
| 1997 | 0 | .020 | .065 |
| 1998 | 0 | .020 | .080 |
| 1999 | 0 | .021 | .088 |
| 2000 | 0 | .019 | .085 |
| 2001 (Site moved to Breckenridge Hills) | |||
| 2001 | 0 | .017 | .064 |
| 2002 | 0 | .0164 | .064 |
| 2003 | 0 | .0158 | .062 |
| 2004 | 0 | .0123 | .049 |
| 2005(Site Shut Down) | |||
Sulfur Dioxide (SO2)
Updated: Only historical data shown below. Instrument has been discontinued.
National Ambient Air Monitoring Standard: A three-hour average of 0.50 ppm (parts per million) and/or a 24-hour average of 0.14 ppm (parts per million) and/or an annual average of 0.03 ppm (parts per million). Data reported in three decimal places must be rounded to two decimal places.
Exceedances allowed without a violation being recorded: One per year.
Disclaimer: Yearly and quarterly data shown below has been subject to data review and validation procedures by the reporting agency. Monthly data and data shown graphically is raw, unreviewed and unvalidated data.
| Year | Number of Exceedances |
Annual Average |
Maximum 24-Hour Average |
Maximum 3-Hour Average |
Maximum 1-Hour Average |
|---|---|---|---|---|---|
| 1993 | 0 | .008 | .033 | .073 | .123 |
| 1994 | 0 | .008 | .024 | .089 | .136 |
| 1995 | 0 | .006 | .024 | .092 | .147 |
| 1996 | 0 | .006 | .026 | .071 | .096 |
| 1997 | 0 | .005 | .030 | .082 | .109 |
| 1998 | 0 | .005 | .032 | .094 | .193 |
| 1999 | 0 | .005 | .030 | .073 | .087 |
| 2000 | 0 | .005 | .021 | .042 | .068 |
| 2001 (Site moved to Brekenridge Hills) | |||||
| 2001 | 0 | .004 | .014 | .036 | .057 |
| 2002 | 0 | .0037 | .023 | .053 | .091 |
| 2003 | 0 | .0033 | .015 | .045 | .090 |
| 2004 | 0 | .0036 | .011 | .040 | .066 |
| 2005(Site Shut Down) | |||||
Carbon Monoxide (CO)
Updated: Only historical data shown below. Instrument has been discontinued.
National Ambient Air Monitoring Standard: A one-hour average of 35 ppm (parts per million) and/or an eight-hour average of 9 ppm (parts per million).
Exceedances allowed without a violation being recorded: None.
Disclaimer: Yearly and quarterly data shown below has been subject to data review and validation procedures by the reporting agency. Monthly data and data shown graphically is raw, unreviewed and unvalidated data.
| Year | Number of Exceedances |
Maximum 8-Hour Average |
Maximum 1-Hour Average |
|---|---|---|---|
| 1993 | 0 | 7.4 | 25.4 |
| 1994 | 1 | 10.0 | 19.5 |
| 1995 | 0 | 5.1 | 8.1 |
| 1996 | 0 | 4.3 | 9.3 |
| 1997 | 0 | 3.9 | 8.0 |
| 1998 | 0 | 4.0 | 10.9 |
| 1999 | 0 | 2.6 | 4.2 |
| 2000 | 0 | 3.5 | 4.3 |
| 2001 (Site moved to Brekenridge Hills) | |||
| 2001 | 0 | 2.4 | 4.7 |
| 2002 | 0 | 3.2 | 6.8 |
| 2003 | 0 | 2.4 | 3.6 |
| 2004 | 0 | 1.9 | 2.6 |
| 2005(Site Shut Down) | |||
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