EPA staff and the Clean Air Scientific Advisory Committee (CASAC) have recommended a new primary National Ambient Air Quality Standard for PM10.
The current standard is based on the average number of times per year PM10 concentrations exceed 150 µg/m3, however
CASAC and EPA believe it is more appropriate to change the standard to a 98th percentile form. A CASAC review in 2010 propounded that setting the 98th
percentile threshold around 75 to 80 µg/m3 would protect the U.S. population to a degree equivalent to the current standard, and
CASAC recommends setting the threshold slightly lower, somewhere in the range of 65 to 75 µg/m3.
Maps of PM10 Concentration 98th Percentile Statistics
To aid in planning for attainment of this proposed PM10 standard, the following North Carolina maps have been drawn showing the 3-year-average
98th percentile of 24-hour concentrations in each county. Click on links for printer-friendly (PDF) version.
North Carolina Counties with 24-hour PM10 Concentrations
N.C. Division of Air Quality • Mailing Address: 1641 Mail Service Center, Raleigh, NC 27699-1641
Physical Address: 217 West Jones Street, Raleigh, NC 27603 • Phone: 919-707-8400 • Fax: 919-707-0718
Email us: DENR.DAQ.Webmaster@lists.ncmail.net