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Virginia Administrative Code
Title 9. Environment
Agency 5. State Air Pollution Control Board
Chapter 30. Ambient Air Quality Standards
11/5/2024

9VAC5-30-70. Oxides of nitrogen with nitrogen dioxide as the indicator.

A. The primary annual ambient air quality standard is 53 parts per billion (ppb), annual average concentration, measured in the ambient air as nitrogen dioxide.

B. The primary 1-hour ambient air quality standard is 100 ppb, 1-hour average concentration, annual arithmetic mean concentration.

C. The secondary ambient air quality standard is 0.053 parts per million (ppm) (100 micrograms per cubic meter), annual arithmetic mean concentration.

D. The levels of the standards shall be measured by a reference method based on Appendix F of 40 CFR Part 50, or by a federal equivalent method (FEM) designated in accordance with 40 CFR Part 53.

E. The annual primary standard is met when the annual average concentration in a calendar year is less than or equal to 53 ppb, as determined in accordance with Appendix S of 40 CFR Part 50 for the annual standard.

F. The 1-hour primary standard is met when the three-year average of the annual 98th percentile of the daily maximum 1-hour average concentration is less than or equal to 100 ppb, as determined in accordance with Appendix S of 40 CFR Part 50 for the 1-hour standard.

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

Statutory Authority

§ 10.1-1308 of the Code of Virginia; §§ 108, 109 and 302 of the Clean Air Act; 40 CFR Parts 50, 53 and 58.

Historical Notes

Derived from VR120-03-07, eff. January 1, 1985; amended, Virginia Register Volume 20, Issue 24, eff. September 8, 2004; Volume 26, Issue 23, eff. August 18, 2010.

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