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Sulfur Dioxide (SO2) Average Values

In 2010, the United States Environmental Protection Agency (USEPA) established the regulatory standard for Sulfur Dioxide (SO2) at a level of 75 parts per billion (ppb) based on a 3-year average of the 99th percentile of 1-hour maximum concentrations.  In North Carolina, the SO2 program has two distinct parts.  The first is the general program, where sites are designed to monitor SO2 levels over large areas such as neighborhoods or cities.  In addition to permanent sites, this program also includes several rotating sites which are monitored for 12-month periods on a rotating basis.  Data from the rotating sites program fail to meet USEPA’s regulatory standard for a 3-year average but are included in the accompanying chart to provide a more complete illustration of SO2 concentrations around the state.  An asterisk (*) is used to denote design values which fail to meet USEPA requirements for completeness.

The second part of the SO2 program falls under USEPA’s Data Requirements Rule (DRR).  This is a relatively new program that is designed to monitor individual facilities whose emission inventory reports indicate that they may emit large quantities of SO2.  This program is designed to enable both North Carolina and USEPA to closely follow a facility’s progress toward meeting the new SO2 standard. Data from industrial sites that do not to meet the 3-year data requirement are not listed on this chart.  Counties which contain industrial sites are indicated on the accompanying map. 

Please click here to open the SO2 Design Values Map as a PDF

County         

Design Values

Beaufort[1,5]

21*

Durham[1]

4

Forsyth[1]

5

Mecklenburg[1,3]

4

Wake[1,3]

3

Cumberland[2]*

2*

Brunswick[4,5]

n/a

Person[4,5]

n/a

Haywood[4,5]

n/a

Buncombe[4,5]

n/a
Purpose of Monitor

[1] SLAMS – (State and Local Monitoring Stations) Network of monitoring stations that monitor ambient air concentrations for pollutants for which standards have been established. The scale of these sites can be either neighborhood or urban.

[2] SPM – (Special Purpose Monitors) SPMs allow the capability of providing monitoring for various reasons such as special studies, modeling verification or compliance status, and other objectives. These monitors are not committed to any one location or for any specified period.

[3] NCORE – (National Core) Community-oriented multi-pollutant monitoring station used to evaluate the regional air quality models used in developing emission strategies and to track trends in air pollution abatement control measures’ impact on improving air quality.

[4] Industrial- Facility-oriented monitoring station used to identify and characterize air quality around large point source emitters to track trends in air pollution abatement control measures' impact on improving air quality.

[5] DRR (Data Requirements Rule)- SO2 Monitors established to meet the data requirements rules by demonstrating attainment with the standard through monitoring for at least 3 years.

Please click here to open the SO2 Design Values Map as a PDF.

County

Design Value

Beaufort[1,5]

22

Durham[1]

6

Forsyth[1]

6     

Lee[2]

2

Mecklenburg[1,3]

5

New Hanover[1]

3

Wake[1,3]

3

Cumberland[2]*

1*

Brunswick[4,5]

n/a

Person[4,5]

n/a

Haywood[4,5]

n/a

Buncombe[4,5]

n/a

Caldwell[2]*

2*

Martin[2]*

2*

Rockingham[2]*

12*

 
2014-2016

2014-2016

In 2010, the United States Environmental Protection Agency (USEPA) established the regulatory standard for Sulfur Dioxide, or SO2, at a level of 75 parts per billion (ppb), based on a 3-year average of the 99th percentile of 1-hour maximum concentrations. 

In North Carolina, the SO2 program has two distinct parts.  The first is the general program, where monitoring sites are designed to monitor SO2 levels over large areas such as neighborhoods or cities.  In addition to these permanent sites, the program also includes several rotating sites which are monitored for 12-month periods on a rotating basis.  Data from the rotating sites program does not meet USEPA’s regulatory standard for a 3-year average but is included in the accompanying chart to provide a more complete illustration of SO2 concentrations around the state.  An asterisk (*) is used to denote rotating sites. 

The second part of the SO2 program falls under USEPA’s Data Requirement Rule (DRR).  This is a relatively new program that is designed to monitor individual facilities whose emission inventory reports indicate that they may emit large quantities of SO2.  This program is designed to enable North Carolina and USEPA to closely follow a facility’s progress toward meeting the new SO2 standard.  At present, no industrial site has completed the requisite 3-year data collection needed to generate a design value.  Data from industrial sites are not listed on the accompanying chart.  Counties with industrial sites are indicated on the accompanying map.

Please click here to open the SO2 Design Values Map as a PDF.

County

Design Value  

Beaufort[1,5]

23

Brunswick[4,5]

n/a

Caldwell[2]*

2*

Chatham[2]*

6*

Cumberland[2]*

1*

Durham[1]

7

Forsyth[1]

9

Lee[2]*

2*

Martin[2]*

3*

Mecklenburg[1,3]

5

New Hanover[1]

3

Person[2]*

3

Rockingham[2]*

14*

Swain[2]*

2*

Wake[1,3]

4

Purpose of Monitor

[1] SLAMS – (State and Local Monitoring Stations) Network of monitoring stations that monitor ambient air concentrations for pollutants for which standards have been established. The scale of these sites can be either neighborhood or urban.

 [2] SPM – (Special Purpose Monitors) SPMs allow the capability of providing monitoring for various reasons such as special studies, modeling verification or compliance status, and other objectives. These monitors are not committed to any one location or for any specified period.

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