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Days exceeding sustainability target for air quality (particulate matter & ozone concentrations)

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PM 2.5Ozone

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2007833

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2008918

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2009711

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2010716

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201139

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2012128

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Ozone notes:

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1. Counts are based on the EPA defined Minnesota ozone season, which runs from April 1 - September 30 for a total of 183 days annually.

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2. Due to the formation characteristics of ozone the MPCA does not monitor for ozone in Minneapolis. Downwind ozone monitors in Blaine, Cedar Creek, Hastings, Shakopee, Stanton, St. Michael, and Stillwater are used in this analysis as they have been sited to capture the maximum ambient concentration for the metro area.

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3. Daily values are based on the maximum 8-hour average concentration at each site. The site with the highest 8-hour average is used to represent the day's concentration. Not all sites have concentration data for each day.

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4. CASAC recommended a range of 60-70 ppb for the 8-hour ozone National Ambient Air Quality Standard. For ease of understanding, the data is organized into AQI categories, as defined by EPA. All values in EPA's "moderate" category exceed the low end of the CASAC recommended range.

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5. Annually, the Twin Cities metropolitan area may experience several days that exceed the level of the National Ambient Air Quality Standard. However, due to the form of the standard (3-year average of the annual 4th-highest value), the Twin Cities metropolitan area currently attains the NAAQS.

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PM2.5 notes:

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1. Not all years have complete daily data.

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2. Data is based on continuous fine particulate monitors at Anderson Elementary and Wenonah School. Monitoring at Wenonah School began in April 2005 and ended December 2009.

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3. Daily values are based on the midnight to midnight 24-hour concentration average. For days when both sites are operational, the site with the highest average will be used to represent the daily concentration.

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4. CASAC recommended a range of 30-35 µg/m3 for the daily fine particle standard. For ease of understanding, the data has been categorized into AQI categories, with the addition of a "high moderate" category to capture the CASAC recommendation.

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5. Annually, Minneapolis experiences several days that exceed the level of the National Ambient Air Quality Standard (days categorized as orange and above). However, due to the form of the standard (98th percentile value averaged over three years), Minneapolis currently attains the NAAQS.