SO2 Average Values for 2011-2013 in NC Counties

In 2010, EPA revised the sulfur dioxide (SO2) standard to a 1-hour standard at a level of 75 parts per billion (ppb). To determine if the standard is met, a continuous 3-year average concentration is calculated from daily measurements and compared to the requirements of the standard. The table below shows the 3-year average SO2 concentration in counties where these sites are located for 2011-2013. SO2 levels in North Carolina are low, ranging from 10 percent to 65 percent of the standard. These values are lower than the previous 3-year period.

Additionally, for many years, SO2. has been measured at several sites across the state on an intermittent basis that does not provide 3-year or longer term averages. This monitoring is conducted at five sites operated for 12 months every 3 years. The overall monitoring conducted at those sites show no exceedances of the standard.

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County 3-Year Average
(99th Percentile)
Beaufort 24 ppb
Forsyth 8 ppb
Mecklenburg 10 ppb
New Hanover 49 ppb
Wake 11 ppb