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National Ambient Air Quality Standards (NAAQS)


Ozone | PM2.5 | PM10 | NO2 | SOx | CO | Pb | TSP

Ozone

Standard
0.075 parts per million (ppm), daily maximum 8-hour average

Attainment Determination Method
The standard is attained at an ambient air quality monitoring site when the average of the annual fourth-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.075 ppm as determined by Appendix I of 40 CFR Part 50, measured according to the method specified in 40 CFR Part 50 Appendix D or equivalent methods established under 40 CFR Part 53.

County Status - Non-Attainment

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Particulate Matter

Fine Particles (PM2.5)
Standards
(1)  15.0 micrograms per cubic meter (ug/m 3), annual arithmetic mean concentration; and

(2)  35 micrograms per cubic meter (ug/m 3), 24-hour average concentration

Attainment Determination Method
These standards are attained when the annual arithmetic mean concentration is less than or equal to 15.0 ug/m 3 and when the 98th percentile 24-hour concentration is less than or equal to 35 ug/m 3, as determined according to Appendix N of 40 CFR Part 50.

County Status - Attainment

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Coarse Particles (PM10)
Standards
150 micrograms per cubic meter (ug/m 3), 24-hour average concentration;  and

Compliance Determination Method
This standard is attained when the 99th percentile 24-hour concentration is less than or equal to 150 ug/m 3, as determined according to Appendix N of 40 CFR Part 50.

County Status - Attainment

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Nitrogen Dioxide (NO 2)

 Standard
(1) 0.053 parts per million (ppm) annual arithmetic mean; and

(2) 100 parts per billion (ppb), 1 hour concentration 

 

 

 

        Attainment Determination Method
        The standard is attained when the annual arithmetic mean concentration in a
         calendar year is less than or equal to 0.053 parts per million, rounded to three
         decimal places (fractional parts equal to or greater than 0.0005 parts per million
         are round up).  To demonstrate attainment, an annual mean must be based on
         hourly data that are at least 75 percent complete or on data derived from
         manual methods that are at least 75 percent complete for the scheduled
         sampling days in each calendar quarter.

County Status - Attainment

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Sulfur Oxides (SO x)

Primary Standards
(1) 0.03 parts per million (ppm) annual arithmetic mean,

(2) 0.14 parts per million (ppm) maximum 24-hour concentration not to be exceeded more than once per year,

 

 

 

         (3) 75 parts per billion (ppb) maximum one-hour concentration. To attain, the
         3-year average of the 99th percentile of the daily maximum 1-hour average at    
         each monitor within an area must not exceed 75 ppb.
         
        Secondary Standards
        (4) 0.05 parts per million (ppm), 3-hour averaging, not to be exceeded more than
         once per year.     

Attainment Determination Method – As stated in the standards

 County Status - Attainment

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Carbon Monoxide (CO)

 Standards
(1)  9 parts per million (10 milligrams per cubic meter) maximum eight-hour average concentration not to be exceeded more than once per year,

(2) 35 parts per million (40 milligrams per cubic meter) maximum one-hour average concentration not to be exceeded more than once per year.

 

 

 

Attainment Determination Method – As stated in the standards

County Status - Attainment

 

 

 

 

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Lead (Pb)

Standards
(1) 1.5 micrograms elemental Lead per cubic meter, maximum arithmetic mean over a calendar quarter; and

(2) 1.5 micrograms per cubic meter, quarterly average

Compliance Determination Method – Per 40 CFR 50 Appendix G.

County Status - Attainment 

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  The State of North Carolina  still has ambient air quality standards for Total Suspended Particulates (TSP):

 (1)     75 micrograms per cubic meter annual geometric mean, and
 (2)     150 micrograms per cubic meter maximum 24-hour concentration not to   be exceeded more than once per year.

 

 

 

 

Refer to MCAPCO Section 2.0400 Ambient Air Quality Standards for further detailed information.

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