Comment on FR Doc # 2010-17970

Dear Sir or Madam, The Gwynns Falls Watershed Association would like to submit our comments regarding the proposed one-year extension for attaining the 1997 8-Hour Ozone standard in the Baltimore region. The Baltimore region was ranked by the American Lung Association as having the 16th worst Ozone quality in the U.S. Further extension of this rule will only lead to further health issues and a reduction in outdoor activity. Our second concern relates to the precision of the data involved in the monitoring of air quality in this region. Specifically the rule states that an extension cannot be made if the 4th highest 8-hour ozone concentration is above 0.084 ppm. The Harford county site 24-025-1001 had concentrations of 0.083 ppm, only 0.001 different from the maximum required to disallow this extension. Because of this our organization asks that the EPA determine if the precision of the instrumentation used to collect this data is within this range of error. Additionally we would like to know the standard error of this measurement to ensure that it complies with the rules. We appreciate your work on this rule and hope that you are able to enforce it in the best way possible to balance economic needs with human and ecosystem health. Best, Marcus Griswold, Ph.D. President, Gwynns Falls Watershed Association