Historical Air Quality Data​

Status of Ozone Pollution in Maryland

T​he Department has developed maps to help you visualize Maryland's air quality impr​ovements. The maps illustrate how lower ozone levels have led to smaller problem areas.Ozone


8-Hour Ozone Exceedance Days

Excel Data The annual list of the 8-hour ozone concentrations exceeding the 2008 health-based National Ambient Air Quality Standard is provided below.  Click on the appropriate check mark to download the data in Excel format.  Be advised that the counts of days reflect all monitors that are part of the non-attainment area (NAA); howe​ver, only Maryland data collected by the Department and the EPA Clean Air Status and Trends Network (CASTNET) are provided in the Excel file.  A map of NAAs shows the Maryland NAAs and surrounding jurisdictions.

Historical air quality data is also accessible at  Clean Air Partners, EPA Air Data,  and other data resources listed below. 

Number of Days 8-Hour Ozone Concentrations Exceeded 2015 Health-Based Standard

 Baltimore, MD NAAWashington, DC-MD-VA NAAPhiladelphia-Wilmington-Atlantic City, PA-DE-MD-NJ NAAState-wideExcel
202315151520 checkmark
20222353 checkmark
17 checkmark
253 checkmark
201912101114 checkmark
201816101716 checkmark
2017981417 checkmark
201621131826 checkmark


15142520 checkmark

Notes: "NAA" denotes non-attainment area, EPA CASTNET data are included since 2011.

Table reflects the 2015 70ppb ozone standard.


Data Resources


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