UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

DATE: May 11, 2011

SUBJECT: Technical Support Document for Virginia’s Amendments to 9VAC5 

Chapter 20 – General Provisions and 9VAC5 Chapter 30 - Ambient Air 

Quality Standards for Nitrogen Dioxide

FROM: Gregory Becoat, Environmental Scientist /s/

Office of Air Program Planning 

TO: File

THRU: Cristina Fernandez, Associate Director /s/

Office of Air Program Planning

A. BACKGROUND 

This technical support document (TSD) evaluates the March 4, 2011 submittal of the 

Virginia State Implementation Plan (SIP) revision pertaining to the ambient air quality 

standard for nitrogen dioxide (NO2).

The Clean Air Act (CAA) specifies that EPA must re-evaluate the appropriateness of its 

various air quality standards every five years. As part of the process, EPA reviewed the 

latest research and determined that revised standards for NO2 were necessary to protect 

public health. EPA revised the level of the primary standard by setting a new 1-hour NO2

standard at a level of 100 parts per billion (ppb) in order to protect against adverse health 

effects associated with short-term exposure to NO2. EPA also retained the current annual 

average NO2 standard of 53 ppb in order to protect against adverse health effects 

associated with long-term exposure to NO2. EPA promulgated the more stringent 

primary national ambient air quality standards (NAAQS) for NO2 on February 9, 2010

(75 FR 6474).

B. STATE SUBMITTAL

On March 4, 2011, the Commonwealth of Virginia submitted a regulation revision A10, 

which consists of amendments to the Commonwealth’s existing regulations in order to 

update the list of appendices under documents incorporated by reference and to add the

new primary 1-hour standard for NO2. Virginia=s revision incorporates the revised NO2

standard into the Code of Virginia (9VAC5 Chapter 30). In addition, the list of 
appendices to 40 CFR part 51 was updated under “Documents incorporated by reference” 

(9VAC5-20-21). The effective date of this regulation is August 18, 2010.

This SIP revision amends regulation 9VAC5-20-21, “Documents incorporated by 

reference” by adding the new Appendix S to the list of federal documents incorporated by 

reference. Appendix S was added to 40 CFR part 50 when the revised NO2 standard was 

promulgated on February 9, 2010 (75 FR 6474).

This SIP revision amends regulation 9VAC5-30-70, “Oxides of nitrogen with nitrogen 

dioxide as the indicator” in order to (1) specify that NO2 is the indicator for oxides of 

nitrogen, (2) limit the 53 ppb standard to the annual primary standard and change the unit 

of measurement from annual arithmetic mean concentration to annual average 

concentration, (3) add the new primary 1-hour standard of 100 ppb, (4) specify reference 

methods used to measure the standard, and (5) specify how the primary annual and 1-

hour standard and the secondary standard are attained.

C. EPA EVALUATION

Virginia’s SIP revisions for the ambient air quality standards for NO2 are consistent with 

the Federal standards.

D. CONCLUSIONS AND RECOMMENDED AGENCY ACTION

This SIP revision request satisfies all requirements for an acceptable SIP revision. EPA 

approval of the SIP revision is recommended.