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Wildfire Haze Over Iowa Dissipates

WINDSOR HEIGHTS – Fine particulate (PM2.5) levels fell across Iowa today.  Yesterday, a plume of smoke originating from Canada wildfires passed southward through the state resulting in unusually high fine particulate levels in  Iowa.

 

The U.S. Environmental Protection Agency’s (EPA) 24-hour health threshold for PM2.5 is 35 micrograms per cubic meter (µg/m3).   Exceedances of this threshold were recorded at several monitoring sites in Iowa on Saturday. Daily average PM2.5 concentrations on Saturday in Waterloo, Cedar Rapids, Viking Lake, Lake Sugema, Des Moines, and Emmetsburg were 37.2, 37.6, 40.0, 47.4, 50.7, and 61.0  µg/m3 respectively. 

EPA uses a simple color scale to further categorize air quality.  Daily average concentrations between 35.5 and 55.4 µg/m3 fall into EPA’s Unhealthy for Sensitive Groups (orange) category.  When air quality is in the orange range, asthmatics, individuals with heart or lung disease, as well as the elderly and children may experience adverse health effects.  Concentrations between 55.5 and 150.4 µg/ m3 fall into EPA’s Unhealthy (red) category. When air quality is in the red range, everyone may experience adverse health effects.  More information about EPA’s air quality index (AQI) is available at: http://www.epa.gov/pm/2012/decfsstandards.pdf.

To generate PM2.5 maps in real time, when data for the entire day is not yet available, EPA uses a surrogate for the 24-hour average concentration, called the NowCast.  To learn more about the NowCast see: http://www.epa.gov/airnow/ani/pm25_aqi_reporting_nowcast_overview.pdf.

Although there is lingering smoke aloft over Northeast Iowa, it is not likely to be mixing towards the surface today.   As of 11 am today, hourly PM2.5 levels across the state have fallen, and air quality is expected to be in the good (green) or moderate (yellow) category for the remainder of the day and tonight.

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