ENCLOSURE 1

COMMONWEALTH OF VIRGINIA

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION

PROVISIONS AFFECTED

REVISION H10

CONCERNING

AMBIENT AIR QUALITY STANDARD FOR SULFUR DIOXIDE

(9VAC5 CHAPTERS 20 AND 30)

Adoption Date: March 18, 2011

Effective Date: May 25, 2011

The following table lists the specific provisions of the attached regulations that will be 

used to implement the State Implementation Plan (SIP). A copy of the actual regulation 

submitted for approval and incorporation by reference into the Virginia SIP is included 

in Enclosure 2.

CHAPTER 20 GENERAL PROVISIONS

PART I Administrative

9VAC5-20-21 Documents incorporated by reference (modified)

CHAPTER 30 AMBIENT AIR QUALITY STANDARDS

9VAC5-30-30 Sulfur oxides (sulfur dioxide) (modified)

TEMPLATES\SIP-REG\REG01

SIP\NONATTN PLANS\2011\H10-SIP-1.DOC
COMMONWEALTH OF VIRGINIA PAGE 1 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

9VAC5 CHAPTER 20.

GENERAL PROVISIONS.

PART I.

Administrative.

9VAC5-20-21. Documents incorporated by reference.

A. The Administrative Process Act and Virginia Register Act provide that state 

regulations may incorporate documents by reference. Throughout these regulations, 

documents of the types specified below have been incorporated by reference.

1. United States Code.

2. Code of Virginia.

3. Code of Federal Regulations.

4. Federal Register.

5. Technical and scientific reference documents.

Additional information on key federal regulations and nonstatutory documents 

incorporated by reference and their availability may be found in subsection E of this 

section.

B. Any reference in these regulations to any provision of the Code of Federal 

Regulations (CFR) shall be considered as the adoption by reference of that provision.

The specific version of the provision adopted by reference shall be that contained in the 

CFR (2010) in effect July 1, 2010. In making reference to the Code of Federal 

Regulations, 40 CFR Part 35 means Part 35 of Title 40 of the Code of Federal 

Regulations; 40 CFR 35.20 means § 35.20 in Part 35 of Title 40 of the Code of Federal 

Regulations.

C. Failure to include in this section any document referenced in the regulations 

shall not invalidate the applicability of the referenced document.

D. Copies of materials incorporated by reference in this section may be 

examined by the public at the central office of the Department of Environmental Quality, 

Eighth Floor, 629 East Main Street, Richmond, Virginia between 8:30 a.m. and 4:30 

p.m. of each business day.

E. Information on federal regulations and nonstatutory documents incorporated 

by reference and their availability may be found below in this subsection.
COMMONWEALTH OF VIRGINIA PAGE 2 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

1. Code of Federal Regulations.

a. The provisions specified below from the Code of Federal 

Regulations (CFR) are incorporated herein by reference.

(1) 40 CFR Part 50 - National Primary and Secondary 

Ambient Air Quality Standards.

(a) Appendix A-1 - Reference Measurement Principle 

and Calibration Procedure for the Measurement of Sulfur Dioxide in the Atmosphere 

(Ultraviolet Fluorescence Method).

(a) Appendix A (b) Appendix A-2 - Reference Method 

for the Determination of Sulfur Dioxide in the Atmosphere (Pararosaniline Method).

(b) (c) Appendix B - Reference Method for the 

Determination of Suspended Particulate Matter in the Atmosphere (High-Volume 

Method).

(c) (d) Appendix C - Measurement Principle and 

Calibration Procedure for the Continuous Measurement of Carbon Monoxide in the 

Atmosphere (Non-Dispersive Infrared Photometry).

(d) (e) Appendix D - Measurement Principle and 

Calibration Procedure for the Measurement of Ozone in the Atmosphere.

(e) (f) Appendix E - Reserved.

(f) (g) Appendix F - Measurement Principle and 

Calibration Procedure for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas 

Phase Chemiluminescence).

(g) (h) Appendix G - Reference Method for the 

Determination of Lead in Suspended Particulate Matter Collected from Ambient Air.

(h) (i) Appendix H - Interpretation of the National 

Ambient Air Quality Standards for Ozone.

(i) (j) Appendix I - Interpretation of the 8-Hour Primary 

and Secondary National Ambient Air Quality Standards for Ozone.

(j) (k) Appendix J - Reference Method for the 

Determination of Particulate Matter as PM10 in the Atmosphere.
COMMONWEALTH OF VIRGINIA PAGE 3 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

(k) (l) Appendix K - Interpretation of the National 

Ambient Air Quality Standards for Particulate Matter.

(l) (m) Appendix L - Reference Method for the 

Determination of Fine Particulate Matter as PM2.5 in the Atmosphere.

(m) (n) Appendix M - Reserved.

(n) (o) Appendix N - Interpretation of the National 

Ambient Air Quality Standards for PM2.5.

(o) (p) Appendix O - Reference Method for the 

Determination of Coarse Particulate Matter as PM in the Atmosphere.

(p) (q) Appendix P - Interpretation of the Primary and 

Secondary National Ambient Air Quality Standards for Ozone.

(q) (r) Appendix Q - Reference Method for the 

Determination of Lead in Suspended Particulate Matter as PM10 Collected from 

Ambient Air.

(r) (s) Appendix R - Interpretation of the National 

Ambient Air Quality Standards for Lead.

(s) (t) Appendix S - Interpretation of the Primary 

National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide).

(u) Appendix T - Interpretation of the Primary National 

Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide).

(2) 40 CFR Part 51 - Requirements for Preparation, 

Adoption, and Submittal of Implementation Plans.

(a) Appendix M - Recommended Test Methods for 

State Implementation Plans.

(b) Appendix S - Emission Offset Interpretive Ruling.

(c) Appendix W - Guideline on Air Quality Models 

(Revised).

(d) Appendix Y - Guidelines for BART Determinations 

Under the Regional Haze Rule.
COMMONWEALTH OF VIRGINIA PAGE 4 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

(3) 40 CFR Part 55 -- Outer Continental Shelf Air 

Regulations.

(4) 40 CFR Part 58 - Ambient Air Quality Surveillance.

Appendix A - Quality Assurance Requirements for 

SLAMS, SPMs and PSD Air Monitoring.

(5) 40 CFR Part 59 - National Volatile Organic Compound 

Emission Standards for Consumer and Commercial Products.

(a) Subpart C - National Volatile Organic Compound 

Emission Standards for Consumer Products.

(b) Subpart D - National Volatile Organic Compound 

Emission Standards for Architectural Coatings, Appendix A--Determination of Volatile 

Matter Content of Methacrylate Multicomponent Coatings Used as Traffic Marking 

Coatings.

(6) 40 CFR Part 60 - Standards of Performance for New 

Stationary Sources.

The specific provisions of 40 CFR Part 60 

incorporated by reference are found in Article 5 (9VAC5-50-400 et seq.) of Part II of 

9VAC5-50 (New and Modified Sources).

(7) 40 CFR Part 61 - National Emission Standards for 

Hazardous Air Pollutants.

The specific provisions of 40 CFR Part 61 

incorporated by reference are found in Article 1 (9VAC5-60-60 et seq.) of Part II of 

9VAC5-60 (Hazardous Air Pollutant Sources).

(8) 40 CFR Part 63 - National Emission Standards for 

Hazardous Air Pollutants for Source Categories.

The specific provisions of 40 CFR Part 63 

incorporated by reference are found in Article 2 (9VAC5-60-90 et seq.) of Part II of

9VAC5-60 (Hazardous Air Pollutant Sources).

(9) 40 CFR Part 64, Compliance Assurance Monitoring.

(10) 40 CFR Part 72, Permits Regulation.
COMMONWEALTH OF VIRGINIA PAGE 5 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

(11) 40 CFR Part 73, Sulfur Dioxide Allowance System.

(12) 40 CFR Part 74, Sulfur Dioxide Opt-Ins.

(13) 40 CFR Part 75, Continuous Emission Monitoring.

(14) 40 CFR Part 76, Acid Rain Nitrogen Oxides Emission 

Reduction Program.

(15) 40 CFR Part 77, Excess Emissions.

(16) 40 CFR Part 78, Appeal Procedures for Acid Rain 

Program.

(17) 40 CFR Part 152, Subpart I, Classification of Pesticides.

(18) 49 CFR Part 172, Hazardous Materials Table. Special 

Provisions, Hazardous Materials Communications, Emergency Response Information, 

and Training Requirements, Subpart E, Labeling.

(19) 29 CFR Part 1926, Subpart F, Fire Protection and 

Prevention.

b. Copies may be obtained from: Superintendent of Documents, 

P.O. Box 371954, Pittsburgh, Pennsylvania 15250-7954; phone (202) 783-3238.

2. U.S. Environmental Protection Agency.

a. The following documents from the U.S. Environmental Protection 

Agency are incorporated herein by reference:

(1) Reich Test, Atmospheric Emissions from Sulfuric Acid 

Manufacturing Processes, Public Health Service Publication No. PB82250721, 1980.

(2) Compilation of Air Pollutant Emission Factors (AP-42). 

Volume I: Stationary and Area Sources, stock number 055-000-00500-1, 1995; 

Supplement A, stock number 055-000-00551-6, 1996; Supplement B, stock number 

055-000-00565, 1997; Supplement C, stock number 055-000-00587-7, 1997; 

Supplement D, 1998; Supplement E, 1999.

(3) "Guidelines for Determining Capture Efficiency" (GD-35),

Emissions Monitoring and Analysis Division, Office of Air Quality Planning and 

Standards, January 9, 1995.
COMMONWEALTH OF VIRGINIA PAGE 6 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

b. Copies of the document identified in subdivision E 2 a (1) of this 

subdivision, and Volume I and Supplements A through C of the document identified in 

subdivision E 2 a (2) of this subdivision, may be obtained from: U.S. Department of 

Commerce, National Technical Information Service, 5285 Port Royal Road, Springfield, 

Virginia 22161; phone 1-800-553-6847. Copies of Supplements D and E of the 

document identified in subdivision E 2 a (2) of this subdivision may be obtained online 

from EPA's Technology Transfer Network at http://www.epa.gov/ttn/index.html. Copies 

of the document identified in subdivision E 2 a (3) of this subdivision are only available 

online from EPA's Technology Transfer Network at 

http://www.epa.gov/ttn/emc/guidlnd.html.

3. U.S. government.

a. The following document from the U.S. government is 

incorporated herein by reference: Standard Industrial Classification Manual, 1987 (U.S. 

Government Printing Office stock number 041-001-00-314-2).

b. Copies may be obtained from: Superintendent of Documents, 

P.O. Box 371954, Pittsburgh, Pennsylvania 15250-7954; phone (202) 512-1800.

4. American Society for Testing and Materials (ASTM).

a. The documents specified below from the American Society for 

Testing and Materials are incorporated herein by reference.

(1) D323-99a, "Standard Test Method for Vapor Pressure of 

Petroleum Products (Reid Method)."

(2) D97-96a, "Standard Test Method for Pour Point of 

Petroleum Products."

(3) D129-00, "Standard Test Method for Sulfur in Petroleum 

Products (General Bomb Method)."

(4) D388-99, "Standard Classification of Coals by Rank."

(5) D396-98, "Standard Specification for Fuel Oils."

(6) D975-98b, "Standard Specification for Diesel Fuel Oils."

(7) D1072-90(1999), "Standard Test Method for Total Sulfur 

in Fuel Gases.”

(8) D1265-97, "Standard Practice for Sampling Liquefied 
COMMONWEALTH OF VIRGINIA PAGE 7 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

Petroleum (LP) Gases (Manual Method)."

(9) D2622-98, "Standard Test Method for Sulfur in 

Petroleum Products by Wavelength Dispersive X-Ray Fluorescence Spectrometry."

(10) D4057-95(2000), "Standard Practice for Manual 

Sampling of Petroleum and Petroleum Products."

(11) D4294-98, "Standard Test Method for Sulfur in 

Petroleum and Petroleum Products by Energy-Dispersive X-Ray Fluorescence 

Spectroscopy."

(12) D523-89, “Standard Test Method for Specular Gloss” 

(1999).

(13) D1613-02, “Standard Test Method for Acidity in Volatile 

Solvents and Chemical Intermediates Used in Paint, Varnish, Lacquer and Related 

Products” (2002).

(14) D1640-95, “Standard Test Methods for Drying, Curing, 

or Film Formation of Organic Coatings at Room Temperature” (1999).

(15) E119-00a, “Standard Test Methods for Fire Tests of 

Building Construction Materials” (2000).

(16) E84-01, “Standard Test Method for Surface Burning 

Characteristics of Building Construction Materials” (2001).

(17) D4214-98, “Standard Test Methods for Evaluating the 

Degree of Chalking of Exterior Paint Films (1998).

(18) D86-04b, “Standard Test Method for Distillation of 

Petroleum Products at Atmospheric Pressure” (2004).

(19) D4359-90, “Standard Test Method for Determining

Whether a Material is a Liquid or a Solid” (reapproved 2000).

(20) E260-96, “Standard Practice for Packed Column Gas 

Chromatography” (reapproved 2001).

(21) D3912-95, "Standard Test Method for Chemical 

Resistance of Coatings Used in Light-Water Nuclear Power Plants" (reapproved 2001).

(22) D4082-02, "Standard Test Method for Effects of 
COMMONWEALTH OF VIRGINIA PAGE 8 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

Gamma Radiation on Coatings for Use in Light-Water Nuclear Power Plants."

(23) F852-99, "Standard Specification for Portable Gasoline 

Containers for Consumer Use" (reapproved 2006).

(24) F976-02, "Standard Specification for Portable Kerosine 

and Diesel Containers for Consumer Use."

(25) D4457-02, "Standard Test Method for Determination of 

Dichloromethane and 1,1,1-Trichloroethane in Paints and Coatings by Direct Injection 

into a Gas Chromatograph" (reapproved 2008).

(26) D3792-05, "Standard Test Method for Water Content of 

Coatings by Direct Injection Into a Gas Chromatograph."

(27) D2879-97, "Standard Test Method for Vapor PressureTemperature Relationship and Initial Decomposition Temperature of Liquids by 

Isoteniscope" (reapproved 2007).

b. Copies may be obtained from: American Society for Testing 

Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428-2959; 

phone (610) 832-9585.

5. American Petroleum Institute (API).

a. The following document from the American Petroleum Institute is 

incorporated herein by reference: Evaporative Loss from Floating Roof Tanks, API 

MPMS Chapter 19, April 1, 1997.

b. Copies may be obtained from: American Petroleum Institute, 

1220 L Street, Northwest, Washington, D.C. 20005; phone (202) 682-8000.

6. American Conference of Governmental Industrial Hygienists (ACGIH)

a. The following document from the ACGIH is incorporated herein 

by reference: 1991-1992 Threshold Limit Values for Chemical Substances and Physical 

Agents and Biological Exposure Indices (ACGIH Handbook).

b. Copies may be obtained from: ACGIH, 1330 Kemper Meadow 

Drive, Suite 600, Cincinnati, Ohio 45240; phone (513) 742-2020.

7. National Fire Prevention Association (NFPA).

a. The documents specified below from the National Fire 
COMMONWEALTH OF VIRGINIA PAGE 9 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

Prevention Association are incorporated herein by reference.

(1) NFPA 385, Standard for Tank Vehicles for Flammable 

and Combustible Liquids, 2000 Edition.

(2) NFPA 30, Flammable and Combustible Liquids Code, 

2000 Edition.

(3) NFPA 30A, Code for Motor Fuel Dispensing Facilities 

and Repair Garages, 2000 Edition.

b. Copies may be obtained from the National Fire Prevention 

Association, One Batterymarch Park, P.O. Box 9101, Quincy, Massachusetts 02269-

9101; phone (617) 770-3000.

8. American Society of Mechanical Engineers (ASME).

a. The documents specified below from the American Society of 

Mechanical Engineers are incorporated herein by reference.

(1) ASME Power Test Codes: Test Code for Steam 

Generating Units, Power Test Code 4.1--1964 (R1991).

(2) ASME Interim Supplement 19.5 on Instruments and 

Apparatus: Application, Part II of Fluid Meters, 6th edition (1971).

(3) Standard for the Qualification and Certification of 

Resource Recovery Facility Operators, ASME QRO-1-1994.

b. Copies may be obtained from the American Society of 

Mechanical Engineers, Three Park Avenue, New York, New York, 10016; phone (800) 

843-2763.

9. American Hospital Association (AHA).

a. The following document from the American Hospital Association 

is incorporated herein by reference: An Ounce of Prevention: Waste Reduction 

Strategies for Health Care Facilities, AHA Catalog no. W5-057007, 1993.

b. Copies may be obtained from: American Hospital Association, 

One North Franklin, Chicago, IL 60606; phone (800) 242-2626.

10. Bay Area Air Quality Management District (BAAQMD).
COMMONWEALTH OF VIRGINIA PAGE 10 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

a. The following documents from the Bay Area Air Quality 

Management District are incorporated herein by reference:

(1) Method 41, “Determination of Volatile Organic 

Compounds in Solvent-Based Coatings and Related Materials Containing 

Parachlorobenzotrifluoride” (December 20, 1995).

(2) Method 43, “Determination of Volatile Methylsiloxanes in 

Solvent-Based Coatings, Inks, and Related Materials” (November 6, 1996).

b. Copies may be obtained from: Bay Area Air Quality Management 

District, 939 Ellis Street, San Francisco, CA 94109, phone (415) 771-6000.

11. South Coast Air Quality Management District (SCAQMD).

a. The following documents from the South Coast Air Quality 

Management District are incorporated herein by reference:

(1) Method 303-91, “Determination of Exempt Compounds,” 

in Manual SSMLLABM, “Laboratory Methods of Analysis for Enforcement Samples” 

(1996).

(2) Method 318-95, “Determination of Weight Percent 

Elemental Metal in Coatings by X-Ray Diffraction,” in Manual SSMLLABM, “Laboratory 

Methods of Analysis for Enforcement Samples” (1996).

(3) Rule 1174 Ignition Method Compliance Certification 

Protocol (February 28, 1991).

(4) Method 304-91, "Determination of Volatile Organic 

Compounds (VOC) in Various Materials," in Manual SSMLLABM, "Laboratory Methods 

of Analysis for Enforcement Samples" (1996).

(5) Method 316A-92, "Determination of Volatile Organic 

Compounds (VOC) in Materials Used for Pipes and Fittings" in Manual SSMLLABM, 

"Laboratory Methods of Analysis for Enforcement Samples" (1996).

(6) "General Test Method for Determining Solvent Losses 

from Spray Gun Cleaning Systems," October 3, 1989.

b. Copies may be obtained from: South Coast Air Quality 

Management District, 21865 E. Copley Drive, Diamond Bar, CA 91765, phone (909) 

396-2000.
COMMONWEALTH OF VIRGINIA PAGE 11 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

12. California Air Resources Board (CARB).

a. The following documents from the California Air Resources 

Board are incorporated herein by reference:

(1) Test Method 510, “Automatic Shut-Off Test Procedure 

for Spill-Proof Systems and Spill-Proof Spouts” (July 6, 2000).

(2) Test Method 511, “Automatic Closure Test Procedure for 

Spill-Proof Systems and Spill-Proof Spouts” (July 6, 2000).

(3) Method 100, "Procedures for Continuous Gaseous 

Emission Stack Sampling" (July 28, 1997).

(4) Test Method 513, "Determination of Permeation Rate for 

Spill-Proof Systems" (July 6, 2000).

(5) Method 310, "Determination of Volatile Organic 

Compounds (VOC) in Consumer Products and Reactive Organic Compounds in 

Aerosol Coating Products (Including Appendices A and B)" (May 5, 2005).

(6) California Code of Regulations, Title 17, Division 3, 

Chapter 1, Subchapter 8.5, Article 1, § 94503.5 (2003).

(7) California Code of Regulations, Title 17, Division 3, 

Chapter 1, Subchapter 8.5, Article 2, §§ 94509 and 94511 (2003).

(8) California Code of Regulations, Title 17, Division 3, 

Chapter 1, Subchapter 8.5, Article 4, §§ 94540-94555 (2003).

(9) "Certification Procedure 501 for Portable Fuel Containers 

and Spill-Proof Spouts, CP-501" (July 26, 2006).

(10) "Test Procedure for Determining Integrity of Spill-Proof 

Spouts and Spill-Proof Systems, TP-501" (July 26, 2006).

(11) "Test Procedure for Determining Diurnal Emissions 

from Portable Fuel Containers, TP-502" (July 26, 2006).

b. Copies may be obtained from: California Air Resources Board, 

P.O. Box 2815, Sacramento, CA 95812, phone (906) 322-3260 or (906) 322-2990.

13. American Architectural Manufacturers Association.
COMMONWEALTH OF VIRGINIA PAGE 12 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

a. The following documents from the American Architectural 

Manufacturers Association are incorporated herein by reference:

(1) Voluntary Specification 2604-02, "Performance 

Requirements and Test Procedures for High Performance Organic Coatings on 

Aluminum Extrusions and Panels" (2002).

(2) Voluntary Specification 2605-02, "Performance 

Requirements and Test Procedures for Superior Performing Organic Coatings on 

Aluminum Extrusions and Panels" (2002).

b. Copies may be obtained from: American Architectural 

Manufacturers Association, 1827 Walden Office Square, Suite 550, Schaumburg, IL 

60173, phone (847) 303-5664.

14. American Furniture Manufacturers Association.

a. The following document from the American Furniture 

Manufacturers Association is incorporated herein by reference: Joint Industry Fabrics 

Standards Committee, Woven and Knit Residential Upholstery Fabric Standards and 

Guidelines (January 2001).

b. Copies may be obtained from: American Furniture 

Manufacturers Association, P.O. Box HP-7, High Point, NC 27261; phone (336) 884-

5000.

9VAC5 CHAPTER 30.

AMBIENT AIR QUALITY STANDARDS.

9VAC5-30-30. Sulfur oxides (sulfur dioxide).

A. The primary ambient air quality standards are as follows:

1. The annual ambient air quality standard is 80 micrograms per cubic 

meter (0.030 parts per million) -- annual arithmetic mean not to be exceeded in a 

calendar year. The annual arithmetic mean shall be rounded to three decimal places 

(fractional parts equal to or greater than 0.0005 ppm shall be rounded up).

2. The 24-hour ambient air quality standard is 365 micrograms per cubic 

meter (0.14 parts per million) -- maximum 24-hour concentration not to be exceeded 

more than once per calendar year. The 24-hour averages shall be determined from 

successive nonoverlapping 24-hour blocks starting at midnight each calendar day and 

shall be rounded to two decimal places (fractional parts equal to or greater than 0.005 

ppm shall be rounded up).
COMMONWEALTH OF VIRGINIA PAGE 13 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

3. The 1-hour annual ambient air quality standard is 75 parts per billion

(ppb), measured in the ambient air as sulfur dioxide (SO2). The 1-hour primary standard 

is met when the three-year average of the annual (99th percentile) of the daily 

maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined 

in accordance with Appendix T of 40 CFR Part 50.

4. The annual and 24-hour ambient air quality standards set forth in 

subdivisions 1 and 2 of this subsection shall no longer apply to an area one year after 

the effective date of designation of that area pursuant to § 107 of the federal Clean Air 

Act for the 1-hour annual ambient air quality standard set forth in subdivision 3 of this 

subsection.

B. The secondary ambient air quality standard is 1,300 micrograms per cubic 

meter (0.50 parts per million) -- maximum three-hour concentration not to be exceeded 

more than once per calendar year. The 3-hour averages shall be determined from 

successive nonoverlapping 3-hour blocks starting at midnight each calendar day and 

shall be rounded to one decimal place (fractional parts equal to or greater than 0.05 

ppm shall be rounded up).

C. Sulfur dioxide shall be measured by the reference method described in 

Appendix A A-1 or A-2 of 40 CFR Part 50, or other method designated as such, or by 

an equivalent method.

D. To demonstrate attainment of the annual and 24-hour primary standard

standards set forth in subdivisions A 1 and 2 of this section, the annual arithmetic mean 

and the second-highest 24-hour averages must be based upon hourly data that are at 

least 75% complete in each calendar quarter. A 24-hour block average shall be 

considered valid if at least 75% of the hourly averages for the 24-hour period are 

available. In the event that only 18, 19, 20, 21, 22, or 23 hourly averages are available, 

the 24-hour block average shall be computed as the sum of the available hourly 

averages using 18, 19, and so on as the divisor. If fewer than 18 hourly averages are 

available, but the 24-hour average would exceed the level of the standard when zeros 

are substituted for the missing values, subject to the rounding rule of subdivision A 2 of 

this section, then this shall be considered a valid 24-hour average. In this case, the 24-

hour block average shall be computed as the sum of the available hourly averages 

divided by 24. Data used for demonstrating attainment of the 1-hour annual primary 

standard set forth in subdivision A 3 of this section shall meet the requirements of

Appendix T of 40 CFR Part 50. 

E. To demonstrate attainment of the secondary standard, the second-highest 3-

hour average must be based upon hourly data that are at least 75% complete in each 

calendar quarter. A 3-hour block average shall be considered valid only if all three 

hourly averages for the 3-hour period are available. If only one or two hourly averages 
COMMONWEALTH OF VIRGINIA PAGE 14 of 14

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-20 AND 30)

are available, but the 3-hour average would exceed the level of the standard when 

zeros are substituted for the missing values, subject to the rounding rule of subsection 

B of this section, then this shall be considered a valid 3-hour average. In all cases, the 

3-hour block average shall be computed as the sum of the hourly averages divided by 

three.

REG\DEV\H10-REG-FIN