PM10 Average Values

In 2012, the United States Environmental Protection Agency (USEPA) reaffirmed the existing regulatory limit for PM₁₀ concentrations.  The standard remained at 150 micrograms per cubic meter (µg/m³) averaged over a 24-hour period.  This value may not be exceeded more than once, on average, per year, over a 3-year period.  The Design Value for PM₁₀ is defined as the number of times the standard is exceeded each calendar year averaged over a 3-year period. Since this number is zero for all counties in North Carolina, to produce a meaningful map, the NC Division of Air Quality began using the 2nd highest, 24-hour average concentration recorded during the latest 3-year period to illustrate PM₁₀ concentrations across the state.  A 2nd highest value of more than 150 µg/m³ would indicate non-attainment of the USEPA standard.  Currently, all sites in North Carolina are in attainment.

To view these PM₁₀ values by county, please select the desired time period below.