COMMONWEALTH OF VIRGINIA

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION

PROVISIONS AFFECTED

REVISION H13

CONCERNING

DEFINITION OF VOC

(9VAC5 CHAPTER 10)

Adoption Date: December 6, 2013

Effective Date: March 12, 2015

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 10 GENERAL DEFINITIONS

9VAC5-10-20 Terms defined

Modified - volatile organic compound

TEMPLATES\FINAL\FR02

REG\DEV\H13-09PF
COMMONWEALTH OF VIRGINIA PAGE 1 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

9VAC5 CHAPTER 10.

GENERAL DEFINITIONS.

9VAC5-10-20. Terms defined.

"Actual emissions rate" means the actual rate of emissions of a pollutant 

from an emissions unit. In general actual emissions shall equal the average rate, in tons 

per year, at which the unit actually emitted the pollutant during the most recent two-year 

period or some other two-year period which is representative of normal source operation.

If the board determines that no two-year period is representative of normal source 

operation, the board shall allow the use of an alternative period of time upon a 

determination by the board that it is more representative of normal source operation.

Actual emissions shall be calculated using the unit's actual operating hours, production 

rates, and types of materials processed, stored, or combusted during the selected time 

period.

"Administrator" means the administrator of the U.S. Environmental 

Protection Agency (EPA) or an authorized representative.

"Affected facility" means, with reference to a stationary source, any part, 

equipment, facility, installation, apparatus, process or operation to which an emission 

standard is applicable or any other facility so designated. The term “affected facility” 

includes any affected source as defined in 40 CFR 63.2.

"Air pollution" means the presence in the outdoor atmosphere of one or 

more substances which are or may be harmful or injurious to human health, welfare or 

safety; to animal or plant life; or to property; or which unreasonably interfere with the 

enjoyment by the people of life or property.

"Air quality" means the specific measurement in the ambient air of a 

particular air pollutant at any given time.

"Air quality control region" means any area designated as such in 9VAC5-

20-200.

"Alternative method" means any method of sampling and analyzing for an 

air pollutant which is not a reference or equivalent method, but which has been 

demonstrated to the satisfaction of the board, in specific cases, to produce results 

adequate for its determination of compliance.

"Ambient air" means that portion of the atmosphere, external to buildings, to 

which the general public has access.
COMMONWEALTH OF VIRGINIA PAGE 2 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

"Ambient air quality standard" means any primary or secondary standard 

designated as such in 9VAC5-30 (Ambient Air Quality Standards).

"Board" means the State Air Pollution Control Board or its designated 

representative.

"Class I area" means any prevention of significant deterioration area (i) in 

which virtually any deterioration of existing air quality is considered significant and (ii) 

designated as such in 9VAC5-20-205.

"Class II area" means any prevention of significant deterioration area (i) in 

which any deterioration of existing air quality beyond that normally accompanying 

well-controlled growth is considered significant and (ii) designated as such in 9VAC5-20-

205.

"Class III area" means any prevention of significant deterioration area (i) in 

which deterioration of existing air quality to the levels of the ambient air quality standards 

is permitted and (ii) designated as such in 9VAC5-20-205.

"Continuous monitoring system" means the total equipment used to sample 

and condition (if applicable), to analyze, and to provide a permanent continuous record of 

emissions or process parameters.

"Control program" means a plan formulated by the owner of a stationary 

source to establish pollution abatement goals, including a compliance schedule to 

achieve such goals. The plan may be submitted voluntarily, or upon request or by order of 

the board, to ensure compliance by the owner with standards, policies and regulations 

adopted by the board. The plan shall include system and equipment information and 

operating performance projections as required by the board for evaluating the probability 

of achievement. A control program shall contain the following increments of progress:

1. The date by which contracts for emission control system or 

process modifications are to be awarded, or the date by which orders are to be issued for 

the purchase of component parts to accomplish emission control or process modification.

2. The date by which the on-site construction or installation of 

emission control equipment or process change is to be initiated.

3. The date by which the on-site construction or installation of 

emission control equipment or process modification is to be completed.
COMMONWEALTH OF VIRGINIA PAGE 3 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

4. The date by which final compliance is to be achieved.

"Criteria pollutant" means any pollutant for which an ambient air quality 

standard is established under 9VAC5-30 (Ambient Air Quality Standards).

"Day" means a 24-hour period beginning at midnight.

"Delayed compliance order" means any order of the board issued after an 

appropriate hearing to an owner which postpones the date by which a stationary source is 

required to comply with any requirement contained in the applicable implementation plan.

"Department" means any employee or other representative of the Virginia 

Department of Environmental Quality, as designated by the director.

"Director" or "executive director" means the director of the Virginia 

Department of Environmental Quality or a designated representative.

"Dispersion technique"

1. Means any technique which attempts to affect the concentration of 

a pollutant in the ambient air by:

a. Using that portion of a stack which exceeds good 

engineering practice stack height;

b. Varying the rate of emission of a pollutant according to 

atmospheric conditions or ambient concentrations of that pollutant; or

c. Increasing final exhaust gas plume rise by manipulating 

source process parameters, exhaust gas parameters, stack parameters, or combining 

exhaust gases from several existing stacks into one stack; or other selective handling of 

exhaust gas streams so as to increase the exhaust gas plume rise.

2. The preceding sentence does not include:

a. The reheating of a gas stream, following use of a pollution 

control system, for the purpose of returning the gas to the temperature at which it was 

originally discharged from the facility generating the gas stream;

b. The merging of exhaust gas streams where:

(1) The owner demonstrates that the facility was 
COMMONWEALTH OF VIRGINIA PAGE 4 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

originally designed and constructed with such merged gas streams;

(2) After July 8, 1985, such merging is part of a change 

in operation at the facility that includes the installation of pollution controls and is 

accompanied by a net reduction in the allowable emissions of a pollutant. This exclusion 

from the definition of "dispersion techniques" shall apply only to the emissions limitation 

for the pollutant affected by such change in operation; or

(3) Before July 8, 1985, such merging was part of a 

change in operation at the facility that included the installation of emissions control 

equipment or was carried out for sound economic or engineering reasons. Where there 

was an increase in the emissions limitation or, in the event that no emissions limitation 

was in existence prior to the merging, an increase in the quantity of pollutants actually 

emitted prior to the merging, the board shall presume that merging was significantly 

motivated by an intent to gain emissions credit for greater dispersion. Absent a 

demonstration by the owner that merging was not significantly motivated by such intent, 

the board shall deny credit for the effects of such merging in calculating the allowable 

emissions for the source;

c. Smoke management in agricultural or silvicultural prescribed 

burning programs;

d. Episodic restrictions on residential woodburning and open burning; 

or

e. Techniques under subdivision 1 c of this definition which increase 

final exhaust gas plume rise where the resulting allowable emissions of sulfur dioxide 

from the facility do not exceed 5,000 tons per year.

"Emergency" means a situation that immediately and unreasonably affects, 

or has the potential to immediately and unreasonably affect, public health, safety or 

welfare; the health of animal or plant life; or property, whether used for recreational, 

commercial, industrial, agricultural or other reasonable use.

"Emissions limitation" means any requirement established by the board 

which limits the quantity, rate, or concentration of continuous emissions of air pollutants, 

including any requirements which limit the level of opacity, prescribe equipment, set fuel 

specifications, or prescribe operation or maintenance procedures to assure continuous 

emission reduction.

"Emission standard" means any provision of 9VAC5-40 (Existing Stationary 

Sources), 9VAC5-50 (New and Modified Stationary Sources), or 9VAC5-60 (Hazardous 
COMMONWEALTH OF VIRGINIA PAGE 5 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

Air Pollutant Sources) which prescribes an emissions limitation, or other requirements 

that control air pollution emissions.

"Emissions unit" means any part of a stationary source which emits or 

would have the potential to emit any air pollutant.

"Equivalent method" means any method of sampling and analyzing for an 

air pollutant which has been demonstrated to the satisfaction of the board to have a 

consistent and quantitative relationship to the reference method under specified 

conditions.

"EPA" means the U.S. Environmental Protection Agency or an authorized 

representative.

"Excess emissions" means emissions of air pollutant in excess of an 

emission standard.

"Excessive concentration" is defined for the purpose of determining good 

engineering practice (GEP) stack height under subdivision 3 of the GEP definition and 

means:

1. For sources seeking credit for stack height exceeding that 

established under subdivision 2 of the GEP definition, a maximum ground-level 

concentration due to emissions from a stack due in whole or part to downwash, wakes, 

and eddy effects produced by nearby structures or nearby terrain features which 

individually is at least 40% in excess of the maximum concentration experienced in the 

absence of such downwash, wakes, or eddy effects and which contributes to a total 

concentration due to emissions from all sources that is greater than an ambient air quality 

standard. For sources subject to the provisions of Article 8 (9VAC5-80-1605 et seq.) of 

Part II of 9VAC5-80 (Permits for Stationary Sources), an excessive concentration 

alternatively means a maximum ground-level concentration due to emissions from a stack 

due in whole or part to downwash, wakes, or eddy effects produced by nearby structures 

or nearby terrain features which individually is at least 40% in excess of the maximum 

concentration experienced in the absence of such downwash, wakes, or eddy effects and 

greater than a prevention of significant deterioration increment. The allowable emission 

rate to be used in making demonstrations under this provision shall be prescribed by the 

new source performance standard that is applicable to the source category unless the 

owner demonstrates that this emission rate is infeasible. Where such demonstrations are 

approved by the board, an alternative emission rate shall be established in consultation 

with the owner;

2. For sources seeking credit after October 11, 1983, for increases in 
COMMONWEALTH OF VIRGINIA PAGE 6 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

existing stack heights up to the heights established under subdivision 2 of the GEP 

definition, either (i) a maximum ground-level concentration due in whole or part to 

downwash, wakes or eddy effects as provided in subdivision 1 of this definition, except 

that the emission rate specified by any applicable implementation plan (or, in the absence 

of such a limit, the actual emission rate) shall be used, or (ii) the actual presence of a 

local nuisance caused by the existing stack, as determined by the board; and

3. For sources seeking credit after January 12, 1979, for a stack 

height determined under subdivision 2 of the GEP definition where the board requires the 

use of a field study or fluid model to verify GEP stack height, for sources seeking stack 

height credit after November 9, 1984, based on the aerodynamic influence of cooling 

towers, and for sources seeking stack height credit after December 31, 1970, based on 

the aerodynamic influence of structures not adequately represented by the equations in 

subdivision 2 of the GEP definition, a maximum ground-level concentration due in whole 

or part to downwash, wakes or eddy effects that is at least 40% in excess of the 

maximum concentration experienced in the absence of such downwash, wakes, or eddy 

effects.

"Existing source" means any stationary source other than a new source or 

modified source.

"Facility" means something that is built, installed or established to serve a 

particular purpose; includes, but is not limited to, buildings, installations, public works, 

businesses, commercial and industrial plants, shops and stores, heating and power 

plants, apparatus, processes, operations, structures, and equipment of all types.

"Federal Clean Air Act" means Chapter 85 (§7401 et seq.) of Title 42 of 

the United States Code.

"Federally enforceable" means all limitations and conditions which are

enforceable by the administrator and citizens under the federal Clean Air Act or that are 

enforceable under other statutes administered by the administrator. Federally enforceable 

limitations and conditions include, but are not limited to, the following:

1. Emission standards, alternative emission standards, alternative 

emissions limitations, and equivalent emissions limitations established pursuant to § 112 

of the federal Clean Air Act as amended in 1990.

2. New source performance standards established pursuant to § 111 

of the federal Clean Air Act, and emission standards established pursuant to § 112 of the 

federal Clean Air Act before it was amended in 1990.
COMMONWEALTH OF VIRGINIA PAGE 7 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

3. All terms and conditions in a federal operating permit, including 

any provisions that limit a source's potential to emit, unless expressly designated as not 

federally enforceable.

4. Limitations and conditions that are part of an implementation plan.

5. Limitations and conditions that are part of a section 111(d) or 

section 111(d)/129 plan.

6. Limitations and conditions that are part of a federal construction 

permit issued under 40 CFR 52.21 or any construction permit issued under regulations 

approved by EPA in accordance with 40 CFR Part 51.

7. Limitations and conditions that are part of an operating permit 

issued pursuant to a program approved by EPA into an implementation plan as meeting 

EPA's minimum criteria for federal enforceability, including adequate notice and 

opportunity for EPA and public comment prior to issuance of the final permit and 

practicable enforceability.

8. Limitations and conditions in a Virginia regulation or program that 

has been approved by EPA under subpart E of 40 CFR Part 63 for the purposes of 

implementing and enforcing § 112 of the federal Clean Air Act.

9. Individual consent agreements issued pursuant to the legal 

authority of EPA.

"Good engineering practice" or "GEP," with reference to the height of the 

stack, means the greater of:

1. 65 meters, measured from the ground-level elevation at the base 

of the stack;

2. a. For stacks in existence on January 12, 1979, and for which the 

owner had obtained all applicable permits or approvals required under 9VAC5-80 

(Permits for Stationary Sources),

Hg = 2.5H,

provided the owner produces evidence that this equation was actually relied on in 

establishing an emissions limitation;

b For all other stacks,
COMMONWEALTH OF VIRGINIA PAGE 8 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

Hg = H + 1.5L,

where:

Hg = good engineering practice stack height, measured from the 

ground-level elevation at the base of the stack,

H = height of nearby structures measured from the ground-level 

elevation at the base of the stack,

L = lesser dimension, height or projected width, of nearby 

structures provided that the board may require the use of a 

field study or fluid model to verify GEP stack height for the 

source; or

3. The height demonstrated by a fluid model or a field study 

approved by the board, which ensures that the emissions from a stack do not result in 

excessive concentrations of any air pollutant as a result of atmospheric downwash, 

wakes, or eddy effects created by the source itself, nearby structures or nearby terrain 

features.

"Hazardous air pollutant" means an air pollutant to which no ambient air 

quality standard is applicable and which in the judgment of the administrator causes, or 

contributes to, air pollution which may reasonably be anticipated to result in an increase in 

mortality or an increase in serious irreversible, or incapacitating reversible, illness.

"Implementation plan" means the portion or portions of the state 

implementation plan, or the most recent revision thereof, which has been approved under 

§ 110 of the federal Clean Air Act, or promulgated under § 110(c) of the federal Clean Air 

Act, or promulgated or approved pursuant to regulations promulgated under § 301(d) of 

the federal Clean Air Act and which implements the relevant requirements of the federal 

Clean Air Act.

"Initial emission test" means the test required by any regulation, permit 

issued pursuant to 9VAC5-80 (Permits for Stationary Sources), control program, 

compliance schedule or other enforceable mechanism for determining compliance with 

new or more stringent emission standards or permit limitations or other emissions

limitations requiring the installation or modification of air pollution control equipment or 

implementation of a control method. Initial emission tests shall be conducted in 

accordance with 9VAC5-40-30.
COMMONWEALTH OF VIRGINIA PAGE 9 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

"Initial performance test" means the test required by (i) 40 CFR Part 60 for 

determining compliance with standards of performance, or (ii) a permit issued pursuant to 

9VAC5-80 (Permits for Stationary Sources) for determining initial compliance with permit 

limitations. Initial performance tests shall be conducted in accordance with 9VAC5-50-30 

and 9VAC5-60-30.

"Isokinetic sampling" means sampling in which the linear velocity of the gas 

entering the sampling nozzle is equal to that of the undisturbed gas stream at the sample 

point.

"Locality" means a city, town, county or other public body created by or 

pursuant to state law.

"Maintenance area" means any geographic region of the United States 

previously designated as a nonattainment area and subsequently redesignated to 

attainment subject to the requirement to develop a maintenance plan and designated as 

such in 9VAC5-20-203.

"Malfunction" means any sudden failure of air pollution control equipment, 

of process equipment, or of a process to operate in a normal or usual manner, which 

failure is not due to intentional misconduct or negligent conduct on the part of the owner 

or other person. Failures that are caused in part by poor maintenance or careless 

operation are not malfunctions.

"Metropolitan statistical area" means any area designated as such in 

9VAC5-20-202.

"Monitoring device" means the total equipment used to measure and record 

(if applicable) process parameters.

"Nearby" as used in the definition of good engineering practice (GEP) is 

defined for a specific structure or terrain feature and:

1. For purposes of applying the formulae provided in subdivision 2 of 

the GEP definition means that distance up to five times the lesser of the height or the 

width dimension of a structure, but not greater than 0.8 kilometers (1/2 mile); and

2. For conducting demonstrations under subdivision 3 of the GEP 

definition means not greater than 0.8 kilometers (1/2 mile), except that the portion of a 

terrain feature may be considered to be nearby which falls within a distance of up to 10 

times the maximum height (Ht) of the feature, not to exceed two miles if such feature 

achieves a height (Ht) 0.8 kilometers from the stack that is at least 40% of the GEP stack 
COMMONWEALTH OF VIRGINIA PAGE 10 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

height determined by the formulae provided in subdivision 2 b of the GEP definition or 26 

meters, whichever is greater, as measured from the ground-level elevation at the base of 

the stack. The height of the structure or terrain feature is measured from the ground-level 

elevation at the base of the stack.

"Nitrogen oxides" means all oxides of nitrogen except nitrous oxide, as 

measured by test methods set forth in 40 CFR Part 60.

"Nonattainment area" means any area which is shown by air quality 

monitoring data or, where such data are not available, which is calculated by air quality 

modeling (or other methods determined by the board to be reliable) to exceed the levels 

allowed by the ambient air quality standard for a given pollutant including, but not limited 

to, areas designated as such in 9VAC5-20-204.

"One hour" means any period of 60 consecutive minutes.

"One-hour period" means any period of 60 consecutive minutes 

commencing on the hour.

"Organic compound" means any chemical compound of carbon excluding 

carbon monoxide, carbon dioxide, carbonic disulfide, carbonic acid, metallic carbides, 

metallic carbonates and ammonium carbonate.

"Owner" means any person, including bodies politic and corporate, 

associations, partnerships, personal representatives, trustees and committees, as well as 

individuals, who owns, leases, operates, controls or supervises a source.

"Particulate matter" means any airborne finely divided solid or liquid material 

with an aerodynamic diameter smaller than 100 micrometers.

"Particulate matter emissions" means all finely divided solid or liquid 

material, other than uncombined water, emitted to the ambient air as measured by the 

applicable reference method, or an equivalent or alternative method.

"PM10" means particulate matter with an aerodynamic diameter less than or 

equal to a nominal 10 micrometers as measured by the applicable reference method or 

an equivalent method.

"PM10 emissions" means finely divided solid or liquid material, with an 

aerodynamic diameter less than or equal to a nominal 10 micrometers emitted to the 

ambient air as measured by the applicable reference method, or an equivalent or 

alternative method.
COMMONWEALTH OF VIRGINIA PAGE 11 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

"Performance test" means a test for determining emissions from new or 

modified sources.

"Person" means an individual, corporation, partnership, association, a 

governmental body, a municipal corporation, or any other legal entity.

"Pollutant" means any substance the presence of which in the outdoor 

atmosphere is or may be harmful or injurious to human health, welfare or safety, to 

animal or plant life, or to property, or which unreasonably interferes with the enjoyment by 

the people of life or property.

"Potential to emit" means the maximum capacity of a stationary source to 

emit a pollutant under its physical and operational design. Any physical or operational 

limitation on the capacity of the source to emit a pollutant, including air pollution control 

equipment, and restrictions on hours of operation or on the type or amount of material 

combusted, stored, or processed, shall be treated as part of its design only if the limitation 

or its effect on emissions is state and federally enforceable.

"Prevention of significant deterioration area" means any area not 

designated as a nonattainment area in 9VAC5-20-204 for a particular pollutant and 

designated as such in 9VAC5-20-205.

"Proportional sampling" means sampling at a rate that produces a constant 

ratio of sampling rate to stack gas flow rate.

"Public hearing" means, unless indicated otherwise, an informal proceeding, 

similar to that provided for in § 2.2-4007.02 of the Administrative Process Act, held to 

afford persons an opportunity to submit views and data relative to a matter on which a 

decision of the board is pending.

"Reference method" means any method of sampling and analyzing for an 

air pollutant as described in the following EPA regulations:

1. For ambient air quality standards in 9VAC5-30 (Ambient Air 

Quality Standards): the applicable appendix of 40 CFR Part 50 or any method that has 

been designated as a reference method in accordance with 40 CFR Part 53, except that it 

does not include a method for which a reference designation has been canceled in 

accordance with 40 CFR 53.11 or 40 CFR 53.16;

2. For emission standards in 9VAC5-40 (Existing Stationary 

Sources) and 9VAC5-50 (New and Modified Stationary Sources): Appendix M of 40 
COMMONWEALTH OF VIRGINIA PAGE 12 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

CFR Part 51 or Appendix A of 40 CFR Part 60; or

3. For emission standards in 9VAC5-60 (Hazardous Air Pollutant 

Sources): Appendix B of 40 CFR Part 61 or Appendix A of 40 CFR Part 63.

"Regional director" means the regional director of an administrative region 

of the Department of Environmental Quality or a designated representative.

"Regulation of the board" means any regulation adopted by the State Air 

Pollution Control Board under any provision of the Code of Virginia.

"Regulations for the Control and Abatement of Air Pollution" means 9VAC5-

10 (General Definitions) through 9VAC5-80 (Permits for Stationary Sources).

"Reid vapor pressure" means the absolute vapor pressure of volatile crude 

oil and volatile nonviscous petroleum liquids except liquefied petroleum gases as 

determined by American Society for Testing and Materials publication, “Standard Test 

Method for Vapor Pressure of Petroleum Products (Reid Method)” (see 9VAC5-20-21).

"Run" means the net period of time during which an emission sample is 

collected. Unless otherwise specified, a run may be either intermittent or continuous 

within the limits of good engineering practice.

"Section 111(d) plan" means the portion or portions of the plan, or the most 

recent revision thereof, which has been approved under 40 CFR 60.27(b) in accordance 

with § 111(d)(1) of the federal Clean Air Act, or promulgated under 40 CFR 60.27(d) in 

accordance with § 111(d)(2) of the federal Clean Air Act, and which implements the 

relevant requirements of the federal Clean Air Act.

"Section 111(d)/129 plan" means the portion or portions of the plan, or the 

most recent revision thereof, which has been approved under 40 CFR 60.27(b) in 

accordance with §§ 111(d)(1) and 129(b)(2) of the federal Clean Air Act, or promulgated 

under 40 CFR 60.27(d) in accordance with §§ 111(d)(2) and 129(b)(3) of the federal 

Clean Air Act, and which implements the relevant requirements of the federal Clean Air 

Act.

"Shutdown" means the cessation of operation of an affected facility for any 

purpose.

"Source" means any one or combination of the following: buildings, 

structures, facilities, installations, articles, machines, equipment, landcraft, watercraft, 

aircraft or other contrivances which contribute, or may contribute, either directly or 
COMMONWEALTH OF VIRGINIA PAGE 13 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

indirectly to air pollution. Any activity by any person that contributes, or may contribute, 

either directly or indirectly to air pollution, including, but not limited to, open burning, 

generation of fugitive dust or emissions, and cleaning with abrasives or chemicals.

"Stack" means any point in a source designed to emit solids, liquids or 

gases into the air, including a pipe or duct, but not including flares.

"Stack in existence" means that the owner had:

1. Begun, or caused to begin, a continuous program of physical on 

site construction of the stack; or

2. Entered into binding agreements or contractual obligations, which 

could not be canceled or modified without substantial loss to the owner, to undertake a 

program of construction of the stack to be completed in a reasonable time.

"Standard conditions" means a temperature of 20°C (68°F) and a pressure 

of 760 millimeters of Hg (29.92 inches of Hg).

"Standard of performance" means any provision of 9VAC5-50 (New and 

Modified Stationary Sources which prescribes an emissions limitation or other 

requirements that control air pollution emissions.

"Startup" means the setting in operation of an affected facility for any 

purpose.

"State enforceable" means all limitations and conditions which are 

enforceable by the board or department, including, but not limited to, those requirements 

developed pursuant to 9VAC5-20-110, requirements within any applicable regulation, 

order, consent agreement or variance, and any permit requirements established pursuant 

to 9VAC5-80 (Permits for Stationary Sources).

"State Implementation Plan" means the plan, including the most recent 

revision thereof, which has been approved or promulgated by the administrator, U.S. 

Environmental Protection Agency, under § 110 of the federal Clean Air Act, and which 

implements the requirements of § 110.

"Stationary source" means any building, structure, facility or installation 

which emits or may emit any air pollutant. A stationary source shall include all of the 

pollutant-emitting activities which belong to the same industrial grouping, are located on 

one or more contiguous or adjacent properties, and are under the control of the same 

person (or persons under common control) except the activities of any vessel.
COMMONWEALTH OF VIRGINIA PAGE 14 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

Pollutant-emitting activities shall be considered as part of the same industrial grouping if 

they belong to the same "major group" (i.e., which have the same two-digit code) as 

described in the Standard Industrial Classification Manual (see 9VAC5-20-21).

"These regulations" means 9VAC5-10 (General Definitions) through 

9VAC5-80 (Permits for Stationary Sources).

"Total suspended particulate (TSP)" means particulate matter as measured 

by the reference method described in Appendix B of 40 CFR Part 50.

"True vapor pressure" means the equilibrium partial pressure exerted by a 

petroleum liquid as determined in accordance with methods described in American 

Petroleum Institute (API) publication, “Evaporative Loss from Floating-Roof Tanks” (see 

9VAC5-20-21). The API procedure may not be applicable to some high viscosity or high 

pour crudes. Available estimates of true vapor pressure may be used in special cases 

such as these.

"Urban area" means any area consisting of a core city with a population of 

50,000 or more plus any surrounding localities with a population density of 80 persons per 

square mile and designated as such in 9VAC5-20-201.

"Vapor pressure," except where specific test methods are specified, means 

true vapor pressure, whether measured directly, or determined from Reid vapor pressure 

by use of the applicable nomograph in American Petroleum Institute publication, 

“Evaporative Loss from Floating-Roof Tanks” (see 9VAC5-20-21).

"Virginia Air Pollution Control Law" means Chapter 13 (§ 10.1- 1300 et seq.) 

of Title 10.1 of the Code of Virginia.

"Volatile organic compound" means any compound of carbon, excluding 

carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and 

ammonium carbonate, which participates in atmospheric photochemical reactions.

1. This includes any such organic compounds which have been 

determined to have negligible photochemical reactivity other than the following:

a. Methane;

b. Ethane;

c. Methylene chloride (dichloromethane);
COMMONWEALTH OF VIRGINIA PAGE 15 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

d. 1,1,1-trichloroethane (methyl chloroform);

e. 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113);

f. Trichlorofluoromethane (CFC-11);

g. Dichlorodifluoromethane (CFC-12);

h. Chlorodifluoromethane (HCFC-22);

i. Trifluoromethane (HFC-23);

j. 1,2-dichloro 1,1,2,2,-tetrafluoroethane (CFC-114);

k. Chloropentafluoroethane (CFC-115);

l. 1,1,1-trifluoro 2,2-dichloroethane (HCFC-123);

m. 1,1,1,2-tetrafluoroethane (HFC-134a);

n. 1,1-dichloro 1-fluoroethane (HCFC-141b);

o. 1-chloro 1,1-difluoroethane (HCFC-142b);

p. 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124);

q. Pentafluoroethane (HFC-125);

r. 1,1,2,2-tetrafluoroethane (HFC-134);

s. 1,1,1-trifluoroethane (HFC-143a);

t. 1,1-difluoroethane (HFC-152a);

u. Parachlorobenzotrifluoride (PCBTF);

v. Cyclic, branched, or linear completely methylated 

siloxanes;

w. Acetone;

x. Perchloroethylene (tetrachloroethylene);
COMMONWEALTH OF VIRGINIA PAGE 16 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

y. 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-225ca);

z. 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb);

aa. 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43-10mee);

bb. Difluoromethane (HFC-32);

cc. Ethylfluoride (HFC-161);

dd. 1,1,1,3,3,3-hexafluoropropane (HFC-236fa);

ee. 1,1,2,2,3-pentafluoropropane (HFC-245ca);

ff. 1,1,2,3,3-pentafluoropropane (HFC-245ea);

gg. 1,1,1,2,3-pentafluoropropane (HFC-245eb);

hh. 1,1,1,3,3-pentafluoropropane (HFC-245fa);

ii. 1,1,1,2,3,3-hexafluoropropane (HFC-236ea);

jj. 1,1,1,3,3-pentafluorobutane (HFC-365mfc);

kk. Chlorofluoromethane (HCFC-31);

ll. 1 chloro-1-fluoroethane (HCFC-151a);

mm. 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a);

nn. 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane 

(C4F9OCH3 or HFE-7100);

oo. 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF3)2CFCF2OCH3);

pp. 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane (C4F9OC2H5

or HFE-7200);

qq. 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF3)2CFCF2OC2H5);
COMMONWEALTH OF VIRGINIA PAGE 17 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

rr. Methyl acetate; 

ss. 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (nC3F7OCH3) (HFE-7000);

tt. 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-

(trifluoromethyl) hexane (HFE-7500);

uu. 1,1,1,2,3,3,3-heptafluoropropane (HFC 227ea);

vv. methyl formate (HCOOCH3);

ww. 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-

trifluoromethyl-pentane (HFE-7300); 

xx. propylene carbonate;

yy. dimethyl carbonate; 

zz. trans-1,3,3,3-tetrafluoropropene; 

aaa. HCF2OCF2H (HFE-134); 

bbb. HCF2OCF2OCF2H (HFE-236cal2); 

ccc. HCF2OCF2CF2OCF2H (HFE-338pcc13); 

ddd. HCF2OCF2OCF2CF2OCF2H (H-Galden 1040x or HGalden ZT 130 (or 150 or 180)); 

eee. trans 1-chloro-3,3,3-trifluoroprop-1-ene;

fff. 2,3,3,3-tetrafluoropropene; and

ggg. Perfluorocarbon compounds which fall into these 

classes:

(1) Cyclic, branched, or linear, completely fluorinated 

alkanes;

(2) Cyclic, branched, or linear, completely fluorinated 
COMMONWEALTH OF VIRGINIA PAGE 18 of 18

STATE AIR POLLUTION CONTROL BOARD

REGULATIONS FOR THE CONTROL AND ABATEMENT OF AIR POLLUTION (9VAC5-10)

ethers with no unsaturations;

(3) Cyclic, branched, or linear, completely fluorinated 

tertiary amines with no unsaturations; and

(4) Sulfur containing perfluorocarbons with no 

unsaturations and with sulfur bonds only to carbon and fluorine.

2. For purposes of determining compliance with emissions 

standards, volatile organic compounds shall be measured by the appropriate reference 

method in accordance with the provisions of 9VAC5-40-30 or 9VAC5-50-30, as 

applicable. Where such a method also measures compounds with negligible 

photochemical reactivity, these negligibly-reactive compounds may be excluded as a 

volatile organic compound if the amount of such compounds is accurately quantified, 

and such exclusion is approved by the board.

3. As a precondition to excluding these compounds as volatile 

organic compounds or at any time thereafter, the board may require an owner to 

provide monitoring or testing methods and results demonstrating, to the satisfaction of 

the board, the amount of negligibly-reactive compounds in the emissions of the source.

4. Exclusion of the above compounds in this definition in effect 

exempts such compounds from the provisions of emission standards for volatile organic 

compounds. The compounds are exempted on the basis of being so inactive that they 

will not contribute significantly to the formation of ozone in the troposphere. However, 

this exemption does not extend to other properties of the exempted compounds which, 

at some future date, may require regulation and limitation of their use in accordance 

with requirements of the federal Clean Air Act.

5. The following compound is a VOC for purposes of all 

recordkeeping, emissions reporting, photochemical dispersion modeling and inventory 

requirements which apply to VOCs and shall be uniquely identified in emission reports, 

but is not a VOC for purposes of VOC emissions standards, VOC emission limitations, 

or VOC content requirements: t-butyl acetate.

"Welfare" means that language referring to effects on welfare includes, but 

is not limited to, effects on soils, water, crops, vegetation, manmade materials, animals, 

wildlife, weather, visibility and climate, damage to and deterioration of property, and 

hazards to transportation, as well as effects on economic values and on personal comfort 

and well-being.

REG\DEV\H13-REG-FIN