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Pinal County Air Quality. August 29, 2007 PM 10 Exceptional Event. August 29, 2007. Strong winds associated with monsoon activity that developed over eastern portions of the county on August 29th. Max winds reached 46 mph which caused two PCAQCD monitors to exceed the 24-hr PM 10 NAAQS.
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Pinal County Air Quality August 29, 2007 PM10 Exceptional Event
August 29, 2007 • Strong winds associated with monsoon activity that developed over eastern portions of the county on August 29th. Max winds reached 46 mph which caused two PCAQCD monitors to exceed the 24-hr PM10 NAAQS. Site 24-hr PM10 Conc. (ug/m3) PCH 253.9 Stanfield 159.4
Location of Stanfield monitor Location of PCH monitor 9 p.m. 8/28/07 to 8 p.m. 8/29/07 local time
8/29/07 “But for” Test • Had it not been “but for” the high winds between 7-9 p.m. associated with the cell development in the county that caused PCH to have a 1-hr PM10 concentration of 5,004 ug/m3, PCH would have NOT exceeded the PM10 24-hr NAAQS. • If the 5,004 ug/m3 was replaced with the average of the other 23 hours then the 24-hr PM10 concentration would be 47 ug/m3 • Stanfield (Avg. of other 22 hrs) - 74 ug/m3
Additional 8/29/07 “But for” Test • PCH had the following 24-hr PM10 concentrations before/after the 8/29/07 event • 8/28/07 – 43.2 ug/m3 • 8/30/07 – 45.8 ug/m3 • Stanfield • 8/28/07 – 48.2 ug/m3 • 8/30/07 – 56.8 ug/m3