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Co-occurrence of Nitrogen Dioxide and Daily PM2.5

Using 2001 data from the EPA AQS database, the daily co-occurrence PM2.5 and NO2 over a 24-h period was characterized. There were 200 sites where PM2.5 and NO2 monitors were co-located. A daily co-occurrence of NO2 and PM2.5 was subjectively defined as when an hourly average NO2 concentration greater than or equal to 0.05 ppm and a PM2.5 24-h concentration equal to or greater than 40 ug/m3 occurred over the same 24-h period. Figure 1 illustrates the daily co-occurrence patterns observed. Using 2001 data from the AQS database, the daily co-occurrence of PM2.5 and NO2 was infrequent.

Figure 1. The co-occurrence pattern for NO2 and PM2.5 using 2001 data from AQS.

The information on this web site can be referenced as Lefohn, A.S. (2006). Co-occurrence of Nitrogen Dioxide and Daily PM2.5. http://www.asl-associates.com/co_occurrence_NO2_PM25.htm.

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