R18-2-101. Definitions

The following definitions apply to this Chapter. Where the same term is defined in this Section and in the definitions Section for 

an Article of this Chapter, the Article-specific definition shall apply.

1. “Act” means the Clean Air Act of 1963 (P.L. 88-206; 42 U.S.C. 7401 through 7671q) as amended through December 31, 

2011 (and no future editions).

2. “Actual emissions” means the actual rate of emissions of a regulated NSR pollutant from an emissions unit, as determined 

in subsections (2)(a) through (e).

a. In general, actual emissions as of a particular date shall equal the average rate, in tons per year, at which the unit 

actually emitted the pollutant during a consecutive 24-month period that precedes the particular date and that is 

representative of normal source operation. The Director may allow the use of a different time period upon a 

determination 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.

b. The Director may presume that source-specific allowable emissions for the unit are equivalent to the actual emissions 

of the unit.

c. For any emissions unit at a Class I source that has not begun normal operations on the particular date, actual emissions 

shall equal the unit’s potential to emit on that date.

d. For any emissions unit at a Class II source that has not begun normal operations on the particular date, actual emissions 

shall be based on applicable control equipment requirements and projected conditions of operation.

e. This definition shall not apply for calculating whether a significant emissions increase has occurred, or for establishing 

a PAL. Instead, the definitions of projected actual emissions and baseline actual emissions in R18-2-401 shall apply 

for those purposes.

3. “Administrator” means the Administrator of the United States Environmental Protection Agency.

4. “Affected facility” means, with reference to a stationary source, any apparatus to which a standard is applicable.

5. “Affected source” means a source that includes one or more units which are subject to emission reduction requirements or 

limitations under Title IV of the Act.

6. “Affected state” means any state whose air quality may be affected by a source applying for a permit, permit revision, or 

permit renewal and that is contiguous to Arizona or that is within 50 miles of the permitted source.

7. “Afterburner” means an incinerator installed in the secondary combustion chamber or stack for the purpose of incinerating 

smoke, fumes, gases, unburned carbon, and other combustible material not consumed during primary combustion.

8. “Air contaminants” means smoke, vapors, charred paper, dust, soot, grime, carbon, fumes, gases, sulfuric acid mist aerosols, 

aerosol droplets, odors, particulate matter, wind-borne matter, radioactive materials, or noxious chemicals, or any other 

material in the outdoor atmosphere.

9. “Air curtain destructor” means an incineration device designed and used to secure, by means of a fan-generated air curtain, 

controlled combustion of only wood waste and slash materials in an earthen trench or refractory-lined pit or bin.

10. “Air pollution” means the presence in the outdoor atmosphere of one or more air contaminants or combinations thereof in 

sufficient quantities, which either alone or in connection with other substances by reason of their concentration and 

duration are or tend to be injurious to human, plant or animal life, or cause damage to property, or unreasonably interfere 

with the comfortable enjoyment of life or property of a substantial part of a community, or obscure visibility, or which 

in any way degrade the quality of the ambient air below the standards established by the director. A.R.S. § 49-421(2).

11. “Air pollution control equipment” means equipment used to eliminate, reduce or control the emission of air pollutants into 

the ambient air.

12. “Air quality control region” (AQCR) means an area so designated by the Administrator pursuant to Section 107 of the Act 

and includes the following regions in Arizona:

a. Maricopa Intrastate Air Quality Control Region which is comprised of the County of Maricopa.

b. Pima Intrastate Air Quality Control Region which is comprised of the County of Pima.

c. Northern Arizona Intrastate Air Quality Control Region which encompasses the counties of Apache, Coconino, Navajo, 

and Yavapai.

d. Mohave-Yuma Intrastate Air Quality Control Region which encompasses the counties of La Paz, Mohave, and Yuma.

e. Central Arizona Intrastate Air Quality Control Region which encompasses the counties of Gila and Pinal.

f. Southeast Arizona Intrastate Air Quality Control Region which encompasses the counties of Cochise, Graham, 

Greenlee, and Santa Cruz.

13. “Allowable emissions” means the emission rate of a stationary source calculated using both the maximum rated capacity 

of the source, unless the source is subject to federally enforceable limits which restrict the operating rate or hours of 

operation, and the most stringent of the following:

a. The applicable standards as set forth in 40 CFR 60, 61 or 63;

b. The applicable existing source performance standard, as approved for the SIP and contained in Article 7 of this Chapter; 

or,

c. The emissions rate specified in any federally promulgated rule or federally enforceable permit conditions applicable 

to the stationary source.

14. “Ambient air” means that portion of the atmosphere, external to buildings, to which the general public has access.
15. “Applicable implementation plan” means those provisions of the state implementation plan approved by the Administrator 

or a federal implementation plan promulgated for Arizona or any portion of Arizona in accordance with Title I of the 

Act.

16. “Applicable requirement” means any of the following:

a. Any federal applicable requirement.

b. Any other requirement established pursuant to this Chapter or A.R.S. Title 49, Chapter 3.

17. “Arizona Testing Manual” means sections 1 and 7 of the Arizona Testing Manual for Air Pollutant Emissions amended 

as of March 1992 (and no future editions).

18. “ASTM” means the American Society for Testing and Materials.

19. “Attainment area” means any area in the state that has been identified in regulations promulgated by the Administrator as 

being in compliance with national ambient air quality standards.

20. “Begin actual construction” means, initiation of physical on-site construction activities on an emissions unit which are of 

a permanent nature. With respect to a change in method of operation this term refers to those onsite activities, other than 

preparatory activities, which mark the initiation of the change.

a. For purposes of title I, parts C and D and section 112 of the clean air act, and for purposes of applicants that require 

permits containing limits designed to avoid the application of title I, parts C and D and section 112 of the clean air 

act, these activities include installation of building supports and foundations, laying of underground pipework, and 

construction of permanent storage structures but do not include any of the following, subject to subsection (20)(c):

i. Clearing and grading, including demolition and removal of existing structures and equipment, stripping and 

stockpiling of topsoil.

ii. Installation of access roads, driveways and parking lots.

iii. Installation of ancillary structures, including fences, office buildings and temporary storage structures, that are 

not a necessary component of an emissions unit or associated air pollution control equipment for which the 

permit is required.

iv. Ordering and onsite storage of materials and equipment.

b. For purposes other than those identified in subsection (20)(a), these activities do not include any of the following, 

subject to subsection (20)(c):

i. Clearing and grading, including demolition and removal of existing structures and equipment, stripping and 

stockpiling of topsoil and earthwork cut and fill for foundations.

ii. Installation of access roads, parking lots, driveways and storage areas.

iii. Installation of ancillary structures, including fences, warehouses, storerooms and office buildings, provided none 

of these structures impacts the design of any emissions unit or associated air pollution control equipment.

iv. Ordering and onsite storage of materials and equipment.

v. Installation of underground pipework, including water, sewer, electric and telecommunications utilities.

vi. Installation of building and equipment supports, including concrete forms, footers, pilings, foundations, pads and 

platforms, provided none of these supports impacts the design of any emissions unit or associated air pollution 

control equipment.

c. An applicant’s performance of any activities that are excluded from the definition of “begin actual construction” under 

subsection (20)(a) or (b) shall be at the applicant’s risk and shall not reduce the applicant’s obligations under this 

Chapter. The director shall evaluate an application for a permit or permit revision and make a decision on the same 

basis as if the activities allowed under subsection (20)(a) or (b) had not occurred. A.R.S. § 49-401.01(7).

21. “Best available control technology” (BACT) means an emission limitation, including a visible emissions standard, based 

on the maximum degree of reduction for each air regulated NSR pollutant which would be emitted from any proposed 

major source or major modification, taking into account energy, environmental, and economic impact and other costs, 

determined by the Director in accordance with R18-2-406(A)(4) to be achievable for such source or modification.

22. “Btu” means British thermal unit, which is the quantity of heat required to raise the temperature of one pound of water 

1°F.

23. “Categorical sources” means the following classes of sources:

a. Coal cleaning plants with thermal dryers;

b. Kraft pulp mills;

c. Portland cement plants;

d. Primary zinc smelters;

e. Iron and steel mills;

f. Primary aluminum ore reduction plants;

g. Primary copper smelters;

h. Municipal incinerators capable of charging more than 250 tons of refuse per day;

i. Hydrofluoric, sulfuric, or nitric acid plants;

j. Petroleum refineries;

k. Lime plants;

l. Phosphate rock processing plants;

m. Coke oven batteries;

n. Sulfur recovery plants;
o. Carbon black plants using the furnace process;

p. Primary lead smelters;

q. Fuel conversion plants;

r. Sintering plants;

s. Secondary metal production plants;

t. Chemical process plants, which shall not include ethanol production facilities that produce ethanol by natural 

fermentation included in North American Industry Classification System codes 325193 or 312140;

u. Fossil-fuel boilers, combinations thereof, totaling more than 250 million Btus per hour heat input;

v. Petroleum storage and transfer units with a total storage capacity more than 300,000 barrels;

w. Taconite preprocessing plants;

x. Glass fiber processing plants;

y. Charcoal production plants;

z. Fossil-fuel-fired steam electric plants and combined cycle gas turbines of more than 250 million Btus per hour heat 

input.

24. “Categorically exempt activities” means any of the following:

a. Any combination of diesel-, natural gas- or gasoline-fired engines with cumulative power equal to or less than 145 

horsepower.

b. Natural gas-fired engines with cumulative power equal to or less than 155 horsepower.

c. Gasoline-fired engines with cumulative power equal to or less than 200 horsepower.

d. Any of the following emergency or stand-by engines used for less than 500 hours in each calendar year, provided the 

permittee keeps records documenting the hours of operation of the engines:

i. Any combination of diesel-, natural gas- or gasoline-fired emergency engines with cumulative power equal to or 

less than 2,500 horsepower.

ii. Natural gas-fired emergency engines with cumulative power equal to or less than 2,700 horsepower.

iii. Gasoline-fired emergency engines with cumulative power equal to or less than 3,700 horsepower.

e. Any combination of boilers with a cumulative maximum design heat input capacity of less than 10 million Btu/hr.

25. “CFR” means the Code of Federal Regulations, amended as of July 1, 2011, (and no future editions), with standard 

references in this Chapter by Title and Part, so that “40 CFR 51” means Title 40 of the Code of Federal Regulations, Part 

51.

26. “Charge” means the addition of metal bearing materials, scrap, or fluxes to a furnace, converter or refining vessel.

27. “Clean coal technology” means any technology, including technologies applied at the precombustion, combustion, or postcombustion stage, at a new or existing facility that will achieve significant reductions in air emissions of sulfur dioxide 

or oxides of nitrogen associated with the utilization of coal in the generation of electricity, or process steam, that was not 

in widespread use as of November 15, 1990.

28. “Clean coal technology demonstration project” means a project using funds appropriated under the heading “Department 

of Energy - Clean Coal Technology,” up to a total amount of $2,500,000,000 for commercial demonstration of clean coal 

technology or similar projects funded through appropriations for the Environmental Protection Agency. The federal 

contribution for a qualifying project shall be at least 20% of the total cost of the demonstration project.

29. “Coal” means all solid fossil fuels classified as anthracite, bituminous, subbituminous, or lignite by ASTM D-388-91, 

(Classification of Coals by Rank).

30. “Combustion” means the burning of matter.

31. “Commence” means, as applied to construction of a source, or a major modification as defined in Article 4 of this Chapter, 

that the owner or operator has all necessary preconstruction approvals or permits and either has:

a. Begun, or caused to begin, a continuous program of actual onsite construction of the source, to be completed within a 

reasonable time; or

b. Entered into binding agreements or contractual obligations, which cannot be cancelled or modified without substantial 

loss to the owner or operator, to undertake a program of actual construction of the source to be completed within a 

reasonable time.

32. “Construction” means any physical change or change in the method of operation, including fabrication, erection, 

installation, demolition, or modification of an emissions unit, which would result in a change in actual emissions.

33. “Continuous monitoring system” means a CEMS, CERMS, or CPMS.

34. “Continuous emissions monitoring system” or “CEMS” means the total equipment, required under the emission 

monitoring provisions in this Chapter, used to sample, condition (if applicable), analyze, and to provide, on a continuous 

basis, a permanent record of emissions.

35. “Continuous emissions rate monitoring system” or “CERMS” means the total equipment required for the determination 

and recording of the pollutant mass emissions rate (in terms of mass per unit of time).

36. “Continuous parameter monitoring system” or “CPMS” means the total equipment, required under the emission 

monitoring provisions in this Chapter, to monitor process or control device operational parameters or other information 

and to provide, on a continuous basis, a permanent record of monitored values.

37. “Controlled atmosphere incinerator” means one or more refractory-lined chambers in which complete combustion is 

promoted by recirculation of gases by mechanical means.
38. “Conventional air pollutant” means any pollutant for which the Administrator has promulgated a primary or secondary 

national ambient air quality standard. A.R.S. § 49-401.01(12).

39. “Department” means the Department of Environmental Quality. A.R.S. § 49-101(2)

40. “Director” means the director of environmental quality who is also the director of the department. A.R.S. § 49-101(3).

41. “Discharge” means the release or escape of an effluent from a source into the atmosphere.

42. “Dust” means finely divided solid particulate matter occurring naturally or created by mechanical processing, handling or 

storage of materials in the solid state.

43. “Dust suppressant” means a chemical compound or mixture of chemical compounds added with or without water to a dust 

source for purposes of preventing air entrainment.

44. “Effluent” means any air contaminant which is emitted and subsequently escapes into the atmosphere.

45. “Electric utility steam generating unit” means any steam electric generating unit that is constructed for the purpose of 

supplying more than one-third of its potential electric output capacity and more than 25 MW electrical output to any 

utility power distribution system for sale. Any steam supplied to a steam distribution system for the purpose of providing 

steam to a steam-electric generator that would produce electrical energy for sale is also considered in determining the 

electrical energy output capacity of the affected facility.

46. “Emission” means an air contaminant or gas stream, or the act of discharging an air contaminant or a gas stream, visible 

or invisible.

47. “Emission standard” or “emission limitation” means a requirement established by the state, a local government, or the 

Administrator which limits the quantity, rate, or concentration of emissions of air pollutants on a continuous basis, 

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

operation or maintenance procedures for a source to assure continuous emission reduction.

48. “Emissions unit” means any part of a stationary source which emits or would have the potential to emit any regulated air 

pollutant and includes an electric steam generating unit.

49. “Equivalent method” means any method of sampling and analyzing for an air pollutant which has been demonstrated under 

R18-2-311(D) to have a consistent and quantitatively known relationship to the reference method, under specified 

conditions.

50. “Excess emissions” means emissions of an air pollutant in excess of an emission standard as measured by the compliance 

test method applicable to such emission standard.

51. “Federal applicable requirement” means any of the following (including requirements that have been promulgated or 

approved by EPA through rulemaking at the time of issuance but have future effective compliance dates):

a. Any standard or other requirement provided for in the applicable implementation plan approved or promulgated by 

EPA through rulemaking under Title I of the Act that implements the relevant requirements of the Act, including 

any revisions to that plan promulgated in 40 CFR 52.

b. Any term or condition of any preconstruction permits issued pursuant to regulations approved or promulgated through 

rulemaking under Title I, including parts C or D, of the Act.

c. Any standard or other requirement under section 111 of the Act, including 111(d).

d. Any standard or other requirement under section 112 of the Act, including any requirement concerning accident 

prevention under section 112(r)(7) of the Act.

e. Any standard or other requirement of the acid rain program under Title IV of the Act or the regulations promulgated 

thereunder and incorporated pursuant to R18-2-333.

f. Any requirements established pursuant to section 504(b) or section 114(a)(3) of the Act.

g. Any standard or other requirement governing solid waste incineration, under section 129 of the Act.

h. Any standard or other requirement for consumer and commercial products, under section 183(e) of the Act.

i. Any standard or other requirement for tank vessels under section 183(f) of the Act.

j. Any standard or other requirement of the program to control air pollution from outer continental shelf sources, under 

section 328 of the Act.

k. Any standard or other requirement of the regulations promulgated to protect stratospheric ozone under Title VI of the 

Act, unless the Administrator has determined that such requirements need not be contained in a Title V permit.

l. Any national ambient air quality standard or increment or visibility requirement under Part C of Title I of the Act, but 

only as it would apply to temporary sources permitted pursuant to section 504(e) of the Act.

52. “Federal Land Manager” means, with respect to any lands in the United States, the secretary of the department with 

authority over such lands.

53. “Federally enforceable” means all limitations and conditions which are enforceable by the Administrator under the Act, 

including all of the following:

a. The requirements of the New Source Performance Standards and National Emission Standards for Hazardous Air 

Pollutants contained in Articles 9 and 11 of this Chapter.

b. The requirements of such other state or county rules or regulations approved by the Administrator, including the 

requirements of state and county operating and new source review permit and registration programs that have been 

approved by the Administrator. Notwithstanding this subsection, the condition of any permit or registration 

designated as being enforceable only by the state is not federally enforceable.

c. The requirements of any applicable implementation plan.
d. Emissions limitations, controls, and other requirements, and any associated monitoring, recordkeeping, and reporting 

requirements, other than those designated as enforceable only by the state, that are included in a permit pursuant to 

R18-2-306.01 or R18-2-306.02.

54. “Federally listed hazardous air pollutant” means a pollutant listed pursuant to R18-2-1701(9).

55. “Final permit” means the version of a permit issued by the Department after completion of all review required by this 

Chapter.

56. “Fixed capital cost” means the capital needed to provide all the depreciable components.

57. “Fuel” means any material which is burned for the purpose of producing energy. 

58. “Fuel burning equipment” means any machine, equipment, incinerator, device or other article, except stationary rotating 

machinery, in which combustion takes place.

59. “Fugitive emissions” means those emissions which could not reasonably pass through a stack, chimney, vent, or other 

functionally equivalent opening.

60. “Fume” means solid particulate matter resulting from the condensation and subsequent solidification of vapors of melted 

solid materials. 

61. “Fume incinerator” means a device similar to an afterburner installed for the purpose of incinerating fumes, gases and 

other finely divided combustible particulate matter not previously burned.

62. “Good engineering practice (GEP) stack height” means a stack height meeting the requirements described in R18-2-332.

63. “Hazardous air pollutant” means any federally listed hazardous air pollutant.

64. “Heat input” means the quantity of heat in terms of Btus generated by fuels fed into the fuel burning equipment under 

conditions of complete combustion.

65. “Incinerator” means any equipment, machine, device, contrivance or other article, and all appurtenances thereof, used for

the combustion of refuse, salvage materials or any other combustible material except fossil fuels, for the purpose of 

reducing the volume of material.

66. “Indian governing body” means the governing body of any tribe, band, or group of Indians subject to the jurisdiction of 

the United States and recognized by the United States as possessing power of self-government.

67. “Indian reservation” means any federally recognized reservation established by Treaty, Agreement, Executive Order, or 

Act of Congress.

68. “Insignificant activity” means any of the following activities:

a. Liquid Storage and Piping

i. Petroleum product storage tanks containing the following substances, provided the applicant lists and identifies 

the contents of each tank with a volume of 350 gallons or more and provides threshold values for throughput 

or capacity or both for each such tank: diesel fuels and fuel oil in storage tanks with capacity of 40,000 gallons 

or less, lubricating oil, transformer oil, and used oil.

ii. Gasoline storage tanks with capacity of 10,000 gallons or less.

iii. Storage and piping of natural gas, butane, propane, or liquified petroleum gas, provided the applicant lists and 

identifies the contents of each stationary storage vessel with a volume of 350 gallons or more and provides 

threshold values for throughput or capacity or both for each such vessel.

iv. Piping of fuel oils, used oil and transformer oil, provided the applicant includes a system description.

v. Storage and handling of drums or other transportable containers where the containers are sealed during storage, 

and covered during loading and unloading, including containers of waste and used oil regulated under the 

federal Resource Conservation and Recovery Act, 42 U.S.C. 6901-6992k. Permit applicants must provide a 

description of material in the containers and the approximate amount stored.

vi. Storage tanks of any size containing exclusively soaps, detergents, waxes, greases, aqueous salt solutions, 

aqueous solutions of acids that are not regulated air pollutants, or aqueous caustic solutions, provided the permit 

applicant specifies the contents of each storage tank with a volume of 350 gallons or more.

vii. Electrical transformer oil pumping, cleaning, filtering, drying and the re-installation of oil back into 

transformers.

b. Internal combustion engine-driven compressors, internal combustion engine-driven electrical generator sets, and 

internal combustion engine-driven water pumps used for less than 500 hours per calendar year for emergency 

replacement or standby service, provided the permittee keeps records documenting the hours of operation of this 

equipment.

c. Low Emitting Processes

i. Batch mixers with rated capacity of 5 cubic feet or less.

ii. Wet sand and gravel production facilities that obtain material from subterranean and subaqueous beds, whose 

production rate is 200 tons/hour or less, and whose permanent in-plant roads are paved and cleaned to control 

dust. This does not include activities in emissions units which are used to crush or grind any non-metallic 

minerals.

iii. Powder coating operations.

iv. Equipment using water, water and soap or detergent, or a suspension of abrasives in water for purposes of 

cleaning or finishing.

v. Blast-cleaning equipment using a suspension of abrasive in water and any exhaust system or collector serving 

them exclusively.
vi. Plastic pipe welding.

d. Site Maintenance

i. Housekeeping activities and associated products used for cleaning purposes, including collecting spilled and 

accumulated materials at the source, including operation of fixed vacuum cleaning systems specifically for 

such purposes.

ii. Sanding of streets and roads to abate traffic hazards caused by ice and snow.

iii. Street and parking lot striping.

iv. Architectural painting and associated surface preparation for maintenance purposes at industrial or commercial 

facilities.

e. Sampling and Testing

i. Noncommercial (in-house) experimental, analytical laboratory equipment which is bench scale in nature, 

including quality control/quality assurance laboratories supporting a stationary source and research and 

development laboratories.

ii. Individual sampling points, analyzers, and process instrumentation, whose operation may result in emissions but 

that are not regulated as emission units.

f. Ancillary Non-Industrial Activities

i. General office activities, such as paper shredding, copying, photographic activities, and blueprinting, but not to 

include incineration.

ii. Use of consumer products, including hazardous substances as that term is defined in the Federal Hazardous 

Substances Act (15 U.S.C. 1261 et seq.) where the product is used at a source in the same manner as normal 

consumer use.

iii. Activities directly used in the diagnosis and treatment of disease, injury or other medical condition.

g. Miscellaneous Activities

i. Installation and operation of potable, process and waste water observation wells, including drilling, pumping, 

filtering apparatus.

ii. Transformer vents.

69. “Kraft pulp mill” means any stationary source which produces pulp from wood by cooking or digesting wood chips in a 

water solution of sodium hydroxide and sodium sulfide at high temperature and pressure. Regeneration of the cooking 

chemicals through a recovery process is also considered part of the kraft pulp mill.

70. “Lead” means elemental lead or alloys in which the predominant component is lead.

71. “Lime hydrator” means a unit used to produce hydrated lime product.

72. “Lime plant” includes any plant which produces a lime product from limestone by calcination. Hydration of the lime 

product is also considered to be part of the source.

73. “Lime product” means any product produced by the calcination of limestone.

74. “Major modification” is defined as follows:

a. A major modification is any physical change in or change in the method of operation of a major source that would 

result in both a significant emissions increase of any regulated NSR pollutant and a significant net emissions increase 

of that pollutant from the stationary source.

b. Any emissions increase or net emissions increase that is significant for nitrogen oxides or volatile organic compounds 

is significant for ozone.

c. For the purposes of this definition, none of the following is a physical change or change in the method of operation:

i. Routine maintenance, repair, and replacement;

ii. Use of an alternative fuel or raw material by reason of an order under sections 2(a) and (b) of the Energy Supply 

and Environmental Coordination Act of 1974, 15 U.S.C. 792, or by reason of a natural gas curtailment plan 

under the Federal Power Act, 16 U.S.C. 792 - 825r;

iii. Use of an alternative fuel by reason of an order or rule under section 125 of the Act;

iv. Use of an alternative fuel at a steam generating unit to the extent that the fuel is generated from municipal solid 

waste;

v. Use of an alternative fuel or raw material by a stationary source that either:

(1) The source was capable of accommodating before December 12, 1976, unless the change would be 

prohibited under any federally enforceable permit condition established after December 12, 1976, under 

40 CFR 52.21, or under Articles 3 or 4 of this Chapter; or

(2) The source is approved to use under any permit issued under 40 CFR 52.21, or under Articles 3 or 4 of this 

Chapter.

vi. An increase in the hours of operation or in the production rate, unless the change would be prohibited under any 

federally enforceable permit condition established after December 12, 1976, under 40 CFR 52.21, or under 

Articles 3 or 4 of this Chapter.

vii. Any change in ownership at a stationary source;

viii. [Reserved.] 

ix. The installation, operation, cessation, or removal of a temporary clean coal technology demonstration project, if 

the project complies with:

(1) The SIP, and
(2) Other requirements necessary to attain and maintain the national ambient air quality standards during the 

project and after it is terminated;

x. For electric utility steam generating units located in attainment and unclassifiable areas only, the installation or 

operation of a permanent clean coal technology demonstration project that constitutes repowering, if the project 

does not result in an increase in the potential to emit any regulated pollutant emitted by the unit. This exemption 

applies on a pollutant-by-pollutant basis; and

xi. For electric utility steam generating units located in attainment and unclassifiable areas only, the reactivation of 

a very clean coal-fired electric utility steam generating unit.

d. This definition shall not apply with respect to a particular regulated NSR pollutant when the major source is complying 

with the requirements of R18-2-412 for a PAL for that regulated NSR pollutant. Instead, the definition of PAL major 

modification in R18-2-401(17) shall apply.

75. “Major source” means:

a. A major source as defined in R18-2-401.

b. A major source under section 112 of the Act:

i. For pollutants other than radionuclides, any stationary source that emits or has the potential to emit, in the 

aggregate, including fugitive emission 10 tons per year (tpy) or more of any hazardous air pollutant which has 

been listed pursuant to section 112(b) of the Act, 25 tpy or more of any combination of such hazardous air 

pollutants, or such lesser quantity as described in Article 11 of this Chapter. Notwithstanding the preceding 

sentence, emissions from any oil or gas exploration or production well (with its associated equipment) and 

emissions from any pipeline compressor or pump station shall not be aggregated with emissions from other 

similar units, whether or not such units are in a contiguous area or under common control, to determine whether 

such units or stations are major sources; or

ii. For radionuclides, “major source” shall have the meaning specified by the Administrator by rule.

c. A major stationary source, as defined in section 302 of the Act, that directly emits or has the potential to emit, 100 tpy

or more of any air pollutant including any major source of fugitive emissions of any such pollutant. The fugitive 

emissions of a stationary source shall not be considered in determining whether it is a major stationary source for 

the purposes of section 302(j) of the Act, unless the source belongs to a section 302(j) category. 

76. “Malfunction” means any sudden and unavoidable failure of air pollution control equipment, process equipment or a 

process to operate in a normal and usual manner, but does not include failures that are caused by poor maintenance, 

careless operation or any other upset condition or equipment breakdown which could have been prevented by the exercise 

of reasonable care.

77. “Minor source” means a source of air pollution which is not a major source for the purposes of Article 4 of this Chapter 

and over which the Director, acting pursuant to A.R.S. § 49-402(B), has asserted jurisdiction.

78. “Minor source baseline area” means the air quality control region in which the source is located.

79. “Mobile source” means any combustion engine, device, machine or equipment that operates during transport and that 

emits or generates air contaminants whether in motion or at rest. A.R.S. § 49-401.01(23).

80. “Modification” or “modify” means a physical change in or change in the method of operation of a source that increases 

the emissions of any regulated air pollutant emitted by such source by more than any relevant de minimis amount or that 

results in the emission of any regulated air pollutant not previously emitted by more than such de minimis amount. An 

increase in emissions at a minor source shall be determined by comparing the source’s potential to emit before and after 

the modification. The following exemptions apply:

a. A physical or operational change does not include routine maintenance, repair or replacement.

b. An increase in the hours of operation or if the production rate is not considered an operational change unless such 

increase is prohibited under any permit condition that is legally and practically enforceable by the department.

c. A change in ownership at a source is not considered a modification. A.R.S. § 49-401.01(24).

81. “Monitoring device” means the total equipment, required under the applicable provisions of this Chapter, used to measure 

and record, if applicable, process parameters.

82. “Motor vehicle” means any self-propelled vehicle designed for transporting persons or property on public highways.

83. “Multiple chamber incinerator” means three or more refractory-lined combustion chambers in series, physically separated 

by refractory walls and interconnected by gas passage ports or ducts.

84. “Natural conditions” includes naturally occurring phenomena that reduce visibility as measured in terms of light extinction, 

visual range, contrast, or coloration.

85. “National ambient air quality standard” means the ambient air pollutant concentration limits established by the 

Administrator pursuant to section 109 of the Act. A.R.S. § 49-401.01(25).

86. “Necessary preconstruction approvals or permits” means those permits or approvals required under the Act and those air 

quality control laws and rules which are part of the SIP.

87. “Net emissions increase” means: 

a. The amount by which the sum of subsections (87)(a)(i) and (ii) exceeds zero:

i. The increase in emissions of a regulated NSR pollutant from a particular physical change or change in the method 

of operation at a stationary source as calculated pursuant to R18-2-402(D); and

ii. Any other increases and decreases in actual emissions of the regulated NSR pollutant at the source that are 

contemporaneous with the particular change and are otherwise creditable.
iii. For purposes of calculating increases and decreases in actual emissions under subsection (87)(a)(ii), baseline 

actual emissions shall be determined as provided in the definition of baseline actual emissions in R18-2-401(2), 

except that subsections R18-2-401(a)(iii) and (b)(iv) shall not apply.

b. An increase or decrease in actual emissions is contemporaneous with the increase from the particular change only if it 

occurs between:

i. The date five years before construction on the particular change commences, and

ii. The date that the increase from the particular change occurs.

c. An increase or decrease in actual emissions is creditable only if the Director has not relied on it in issuing a permit, 

which is in effect when the increase in actual emissions from the particular change occurs. 

d. An increase or decrease in actual emissions of sulfur dioxide, nitrogen oxides, or PM10 which occurs before the 

applicable baseline date, as described in R18-2-218, is creditable only if it is required to be considered in calculating 

the amount of maximum allowable increases remaining available.

e. An increase in actual emissions is creditable only to the extent that the new level of actual emissions exceeds the old 

level.

f. A decrease in actual emissions is creditable only to the extent that it satisfies all of the following conditions:

i. The old level of actual emissions or the old level of allowable emissions, whichever is lower, exceeds the new 

level of actual emissions.

ii. It is enforceable as a practical matter at and after the time that actual construction on the particular change begins.

iii. It has approximately the same qualitative significance for public health and welfare as that attributed to the 

increase from the particular change.

iv. The emissions unit was actually operated and emitted the specific pollutant.

v. For a source located in an area designated as nonattainment for the regulated NSR pollutant, the Director has not 

relied on it in issuing any permit under Article 4 or R18-2-334, and the state has not relied on it in demonstrating 

attainment or reasonable further progress.

g. An increase that results from a physical change at a source occurs when the emissions unit on which construction 

occurred becomes operational and begins to emit a particular pollutant. Any emissions unit that replaces an existing 

emissions unit and that requires shakedown becomes operational only after a reasonable shakedown period, not to 

exceed 180 days.

88. “New source” means any stationary source of air pollution which is subject to an applicable new source performance 

standard under Article 9 of this Chapter.

89. “Nitric acid plant” means any facility producing nitric acid 30% to 70% in strength by either the pressure or atmospheric

pressure process.

90. “Nitrogen oxides” means all oxides of nitrogen except nitrous oxide, as measured by test methods set forth in the 

Appendices to 40 CFR 60.

91. “Nonattainment area” means an area so designated by the Administrator acting pursuant to section 107 of the Act as 

exceeding national primary or secondary ambient air standards for a particular pollutant or pollutants.

92. “Nonpoint source” means a source of air contaminants which lacks an identifiable plume or emission point.

93. “Opacity” means the degree to which emissions reduce the transmission of light and obscure the view of an object in the 

background.

94. “Operation” means any physical or chemical action resulting in the change in location, form, physical properties, or 

chemical character of a material.

95. “Owner or operator” means any person who owns, leases, operates, controls, or supervises an affected facility or a 

stationary source.

96. “Particulate matter” means any airborne finely divided solid or liquid material with an aerodynamic diameter smaller than

100 micrometers.

97. “Particulate matter emissions” means all finely divided solid or liquid materials other than uncombined water, emitted to 

the ambient air as measured by applicable test methods and procedures described in R18-2-311.

98. “Permitting authority” means the department or a county department, agency or air pollution control district that is charged 

with enforcing a permit program adopted pursuant to A.R.S. § 49-480(A). A.R.S. § 49-401.01(28).

99. “Permitting exemption thresholds” for a regulated minor NSR pollutant means the following:

Regulated Air

Pollutant

Emission Rate 

in tons per year (TPY)

PM2.5 (primary emissions only; levels for precursors are set below) 5

PM10 7.5

SO2 20

NOx 20

VOC 20
CO 50

Pb 0.3

100. “Person” means any public or private corporation, company, partnership, firm, association or society of persons, the 

federal government and any of its departments or agencies, the state and any of its agencies, departments or political 

subdivisions, as well as a natural person.

101. “Planning agency” means an organization designated by the governor pursuant to 42 U.S.C. 7504. A.R.S. § 49-

401.01(29).

102. “Predictive Emissions Monitoring System” or “PEMS” means the total equipment, required under the emission 

monitoring provisions in this Chapter, to monitor process and control device operational parameters and other 

information, and calculate and record the mass emissions rate on a continuous basis.

103. “PM2.5” means particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers as 

measured by a reference method based on 40 CFR 50 Appendix L, or by an equivalent method designated according to 

40 CFR 53.

104. “PM10” means particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers as 

measured by a reference method contained within 40 CFR 50 Appendix J or by an equivalent method designated in 

accordance with 40 CFR 53.

105. “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 applicable test methods and procedures described in 

R18-2-311.

106. “Plume” means visible effluent.

107. “Pollutant” means an air contaminant the emission or ambient concentration of which is regulated pursuant to this 

Chapter.

108. “Portable source” means any building, structure, facility, or installation subject to regulation pursuant to A.R.S. § 49-426 

which emits or may emit any air pollutant and is capable of being operated at more than one location.

109. “Potential to emit” or “potential emission rate” means the maximum capacity of a stationary source to emit a pollutant, 

excluding secondary emissions, 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 if the limitation 

or the effect it would have on emissions is legally and practically enforceable by the Department or a county under A.R.S. 

Title 49, Chapter 3; any rule, ordinance, order or permit adopted or issued under A.R.S. Title 49, Chapter 3 or the state 

implementation plan. 

110. “Primary ambient air quality standards” means the ambient air quality standards which define levels of air quality 

necessary, with an adequate margin of safety, to protect the public health, as specified in Article 2 of this Chapter.

111. “Process” means one or more operations, including equipment and technology, used in the production of goods or services 

or the control of by-products or waste.

112. “Project” means a physical change in, or change in the method of operation of, an existing major source.

113. “Proposed permit” means the version of a permit for which the Director offers public participation under R18-2-330 or 

affected state review under R18-2-307(D).

114. “Proposed final permit” means the version of a Class I permit or Class I permit revision that the Department proposes to 

issue and forwards to the Administrator for review in compliance with R18-2-307(A).

115. “Reactivation of a very clean coal-fired electric utility steam generating unit” means any physical change or change in 

the method of operation associated with commencing commercial operations by a coal-fired utility unit after a period of 

discontinued operation if the unit:

a. Has not been in operation for the two-year period before enactment of the Clean Air Act Amendments of 1990, and 

the emissions from the unit continue to be carried in the Director’s emissions inventory at the time of enactment;

b. Was equipped before shutdown with a continuous system of emissions control that achieves a removal efficiency for 

sulfur dioxide of no less than 85% and a removal efficiency for particulates of no less than 98%;

c. Is equipped with low-NOx burners before commencement of operations following reactivation; and

d. Is otherwise in compliance with the Act.

116. “Reasonable further progress” means the schedule of emission reductions defined within a nonattainment area plan as 

being necessary to come into compliance with a national ambient air quality standard by the primary standard attainment 

date.

117. “Reasonably available control technology” (RACT) means devices, systems, process modifications, work practices or 

other apparatus or techniques that are determined by the Director to be reasonably available taking into account:

a. The necessity of imposing the controls in order to attain and maintain a national ambient air quality standard;

b. The social, environmental, energy and economic impact of the controls;

c. Control technology in use by similar sources; and

d. The capital and operating costs and technical feasibility of the controls.

118. “Reclaiming machinery” means any machine, equipment device or other article used for picking up stored granular 

material and either depositing this material on a conveyor or reintroducing this material into the process.
119. “Reference method” means the methods of sampling and analyzing for an air pollutant as described in the Arizona Testing 

Manual; 40 CFR 50, Appendices A through K; 40 CFR 51, Appendix M; 40 CFR 52, Appendices D and E; 40 CFR 60, 

Appendices A through F; and 40 CFR 61, Appendices B and C, as incorporated by reference in 18 A.A.C. 2, Appendix 

2.

120. “Regulated air pollutant” means any of the following:

a. Any conventional air pollutant.

b. Nitrogen oxides and volatile organic compounds.

c. Any air contaminant that is subject to a standard contained in Article 9 of this Chapter.

d. Any hazardous air pollutant as defined in Article 17 of this Chapter.

e. Any Class I or II substance listed in section 602 of the Act.

121. “Regulated minor NSR pollutant” means any pollutant for which a national ambient air quality standard has been 

promulgated and the following precursors for such pollutants:

a. VOC and nitrogen oxides as precursors to ozone.

b. Nitrogen oxides and sulfur dioxide as precursors to PM2.5.

122. “Regulated NSR pollutant” means any of the following:

a. Any pollutant for which a national ambient air quality standard has been promulgated and any pollutant identified 

under this subsection as a constituent or precursor to such pollutant. Precursors for purposes of NSR are the 

following:

i. Volatile organic compounds and nitrogen oxides are precursors to ozone in all areas.

ii. Sulfur dioxide is a precursor to PM2.5 in all areas.

iii. Nitrogen oxides are precursors to PM2.5 in all areas.

b. Any pollutant that is subject to any standard promulgated under Article 9 of this Chapter.

c. Any Class I or II substance subject to a standard promulgated under or established by Title VI of the Act as of July 1, 

2011.

d. [Reserved.]

e. Notwithstanding subsections (122)(a) through (d), the term regulated NSR pollutant shall not include any or all 

hazardous air pollutants listed under R18-2-1101, unless the listed hazardous air pollutant is also regulated as a 

constituent or precursor of a general pollutant listed under section 108 of the Act as of July 1, 2010.

f. Particulate matter emissions, PM2.5 emissions, and PM10 emissions shall include gaseous emissions from a source or 

activity which condense to form particulate matter at ambient temperatures. On and after January 1, 2011, 

condensable particulate matter shall be accounted for in applicability determinations and in establishing emissions 

limitations for particulate matter, PM2.5 and PM10 in permits issued under Article 4.

123. “Repowering” means:

a. Replacing an existing coal-fired boiler with one of the following clean coal technologies:

i. Atmospheric or pressurized fluidized bed combustion;

ii. Integrated gasification combined cycle;

iii. Magnetohydrodynamics;

iv. Direct and indirect coal-fired turbines;

v. Integrated gasification fuel cells; or

vi. As determined by the Administrator, in consultation with the United States Secretary of Energy, a derivative of 

one or more of the above technologies; and

vii. Any other technology capable of controlling multiple combustion emissions simultaneously with improved 

boiler or generation efficiency and with significantly greater waste reduction relative to the performance of 

technology in widespread commercial use as of November 15, 1990.

b. Repowering also includes any oil, gas, or oil and gas-fired unit that has been awarded clean coal technology 

demonstration funding as of January 1, 1991, by the United States Department of Energy.

c. The Director shall give expedited consideration to permit applications for any source that satisfies the requirements of 

this subsection and is granted an extension under section 409 of the Act.

124. “Run” means the net period of time during which an emission sample is collected, which may be, unless otherwise 

specified, either intermittent or continuous within the limits of good engineering practice.

125. “SCREEN model” means the AERSCREEN air dispersion model published by the Administrator in April 2011 and 

available on the Support Center for Regulatory Atmospheric Modeling web site: http://www.epa.gov/ttn/scram.

126. “Secondary ambient air quality standards” means the ambient air quality standards which define levels of air quality 

necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant, as specified in Article

2 of this Chapter.

127. “Secondary emissions” means emissions which are specific, well defined, quantifiable, occur as a result of the 

construction or operation of a major source or major modification, but do not come from the major source or major 

modification itself, and impact the same general area as the stationary source or modification which causes the secondary 

emissions. Secondary emissions include emissions from any offsite support facility which would not otherwise be 

constructed or increase its emissions as a result of the construction or operation of the major source or major modification. 

Secondary emissions do not include any emissions which come directly from a mobile source, such as emissions from 

the tailpipe of a motor vehicle, from a train, or from a vessel.
128. “Section 302(j) category” means:

a. Any of the classes of sources listed in the definition of categorical source in subsection (23); or

b. Any category of affected facility which, as of August 7, 1980, is being regulated under section 111 or 112 of the Act.

129. “Shutdown” means the cessation of operation of any air pollution control equipment or process equipment for any 

purpose, except routine phasing out of process equipment.

130. “Significant” means, in reference to a significant emissions increase, a net emissions increase or a stationary source’s

potential to emit a regulated NSR pollutant:

a. A rate of emissions that would equal or exceed any of the following rates:

Pollutant Emissions Rate

Carbon monoxide 100 tons per year (tpy)

Nitrogen oxides 40 tpy

Sulfur dioxide 40 tpy

Particulate matter 25 tpy

PM10 15 tpy

PM2.5 10 tpy of direct PM2.5 emissions; 40 tpy of sulfur dioxide 

emissions; 40 tpy of nitrogen oxide emissions.

VOC 40 tpy 

Lead 0.6 tpy

Fluorides 3 tpy

Sulfuric acid mist 7 tpy

Hydrogen sulfide (H2S) 10 tpy

Total reduced sulfur

(including H2S) 10 tpy

Reduced sulfur compounds (including H2S) 10 tpy

Municipal waste combustor organics (measured as total tetra-through 

octa-chlorinated dibenzo-p-dioxins and dibenzofurans) 3.5 x 10-6

tpy

Municipal waste combustor

metals (measured as particulate matter) 15 tpy

Municipal waste combustor acid gases (measured as sulfur

dioxide and hydrogen chloride) 40 tpy

Municipal solid waste landfill emissions (measured as nonmethane 

organic compounds) 50 tpy

b. In ozone nonattainment areas classified as serious or severe, significant emissions of nitrogen oxides and VOC shall 

be determined under R18-2-405.

c. In a carbon monoxide nonattainment area classified as serious, a rate of emissions that would equal or exceed 50 tons 

per year, if the Administrator has determined that stationary sources contribute significantly to carbon monoxide 

levels in that area.

d. For a regulated NSR pollutant that is not listed in subsection (130)(a), any emission rate.

e. Notwithstanding the emission rates listed in subsection (130)(a), any emissions rate or any net emissions increase 

associated with a major source or major modification, which would be constructed within 10 kilometers of a Class 

I area and have an impact on the ambient air quality of such area equal to or greater than 1 mg/m3 (24-hour average).

131. “Significant emissions increase” means, for a regulated NSR pollutant, an increase in emissions that is significant as 

defined in this Section for that pollutant.

132. “Smoke” means particulate matter resulting from incomplete combustion.

133. “Source” means any building, structure, facility or installation that may cause or contribute to air pollution or the use of 

which may eliminate, reduce or control the emission of air pollution. A.R.S. § 49-401.01(23).

134. “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.

135. “Stack in existence” means that the owner or operator had either:

a. Begun, or caused to begin, a continuous program of physical onsite construction of the stack;

b. Entered into binding agreements or contractual obligations, which could not be cancelled or modified without 

substantial loss to the owner or operator, to undertake a program of construction of the stack to be completed in a 

reasonable time.

136. “Start-up” means the setting into operation of any air pollution control equipment or process equipment for any purpose 

except routine phasing in of process equipment.
137. “State implementation plan” or “SIP” means the accumulated record of enforceable air pollution control measures, 

programs and plans adopted by the Director and submitted to and approved by the Administrator pursuant to 42 U.S.C. 

7410.

138. “Stationary rotating machinery” means any gas engine, diesel engine, gas turbine, or oil fired turbine operated from a 

stationary mounting and used for the production of electric power or for the direct drive of other equipment.

139. “Stationary source” means any building, structure, facility or installation subject to regulation pursuant to A.R.S. § 49-

426(A) which emits or may emit any air pollutant. “Building,” “structure,” “facility,” or “installation” means 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. Pollutant-emitting 

activities shall be considered as part of the same industrial grouping if they belong to the same “Major Group” as 

described in the “Standard Industrial Classification Manual, 1987.”

140. “Sulfuric acid plant” means any facility producing sulfuric acid by the contact process by burning elemental sulfur, 

alkylation acid, hydrogen sulfide, or acid sludge, but does not include facilities where conversion to sulfuric acid is 

utilized as a means of preventing emissions of sulfur dioxide or other sulfur compounds to the atmosphere.

141. “Temporary clean coal technology demonstration project” means a clean coal technology demonstration project operated 

for five years or less, and that complies with the applicable implementation plan and other requirements necessary to 

attain and maintain the national ambient air quality standards during the project and after the project is terminated.

142. “Temporary source” means a source which is portable, as defined in A.R.S. § 49-401.01(23) and which is not an affected 

source.

143. “Total reduced sulfur” (TRS) means the sum of the sulfur compounds, primarily hydrogen sulfide, methyl mercaptan, 

dimethyl sulfide, and dimethyl disulfide, that are released during kraft pulping and other operations and measured by 

Method 16 in 40 CFR 60, Appendix A.

144. “Trivial activities” means activities and emissions units, such as the following, that may be omitted from a permit or 

registration application. Certain of the following listed activities include qualifying statements intended to exclude similar 

activities:

a. Low-Emitting Combustion

i. Combustion emissions from propulsion of mobile sources;

ii. Emergency or backup electrical generators at residential locations;

iii. Portable electrical generators that can be moved by hand from one location to another. “Moved by hand” means 

capable of being moved without the assistance of any motorized or non-motorized vehicle, conveyance, or 

device;

b. Low- Or Non-Emitting Industrial Activities

i. Blacksmith forges;

ii. Hand-held or manually operated equipment used for buffing, polishing, carving, cutting, drilling, sawing, 

grinding, turning, routing or machining of ceramic art work, precision parts, leather, metals, plastics, 

fiberboard, masonry, carbon, glass, or wood;

iii. Brazing, soldering, and welding equipment, and cutting torches related to manufacturing and construction 

activities that do not result in emission of HAP metals. Brazing, soldering, and welding equipment, and cutting 

torches related to manufacturing and construction activities that emit HAP metals are insignificant activities 

based on size or production level thresholds. Brazing, soldering, and welding equipment, and cutting torches 

directly related to plant maintenance and upkeep and repair or maintenance shop activities that emit HAP metals 

are treated as trivial and listed separately in this definition;

iv. Drop hammers or hydraulic presses for forging or metalworking;

v. Air compressors and pneumatically operated equipment, including hand tools;

vi. Batteries and battery charging stations, except at battery manufacturing plants;

vii. Drop hammers or hydraulic presses for forging or metalworking;

viii. Equipment used exclusively to slaughter animals, not including other equipment at slaughterhouses, such as 

rendering cookers, boilers, heating plants, incinerators, and electrical power generating equipment;

ix. Hand-held applicator equipment for hot melt adhesives with no VOC in the adhesive formulation;

x. Equipment used for surface coating, painting, dipping, or spraying operations, except those that will emit VOC 

or HAP;

xi. CO2 lasers used only on metals and other materials that do not emit HAP in the process;

xii. Electric or steam-heated drying ovens and autoclaves, but not the emissions from the articles or substances being 

processed in the ovens or autoclaves or the boilers delivering the steam;

xiii. Salt baths using nonvolatile salts that do not result in emissions of any regulated air pollutants;

xiv. Laser trimmers using dust collection to prevent fugitive emissions;

xv. Process water filtration systems and demineralizers;

xvi. Demineralized water tanks and demineralizer vents;

xvii. Oxygen scavenging or de-aeration of water;

xviii. Ozone generators;

xix. Steam vents and safety relief valves;

xx. Steam leaks; and
xxi. Steam cleaning operations and steam sterilizers;

xxii. Use of vacuum trucks and high pressure washer/cleaning equipment within the stationary source boundaries 

for cleanup and in-source transfer of liquids and slurried solids to waste water treatment units or conveyances;

xxiii. Equipment using water, water and soap or detergent, or a suspension of abrasives in water for purposes of 

cleaning or finishing.

xxiv. Electric motors.

c. Building and Site Maintenance Activities

i. Plant and building maintenance and upkeep activities, including grounds-keeping, general repairs, cleaning, 

painting, welding, plumbing, re-tarring roofs, installing insulation, and paving parking lots, if these activities 

are not conducted as part of a manufacturing process, are not related to the source’s primary business activity, 

and do not otherwise trigger a permit revision. Cleaning and painting activities qualify as trivial activities if 

they are not subject to VOC or hazardous air pollutant control requirements;

ii. Repair or maintenance shop activities not related to the source’s primary business activity, not including emissions 

from surface coating, de-greasing, or solvent metal cleaning activities, and not otherwise triggering a permit 

revision;

iii. Janitorial services and consumer use of janitorial products;

iv. Landscaping activities;

v. Routine calibration and maintenance of laboratory equipment or other analytical instruments;

vi. Sanding of streets and roads to abate traffic hazards caused by ice and snow;

vii. Street and parking lot striping;

viii. Caulking operations which are not part of a production process.

d. Incidental, Non-Industrial Activities

i. Air-conditioning units used for human comfort that do not have applicable requirements under Title VI of the Act;

ii. Ventilating units used for human comfort that do not exhaust air pollutants into the ambient air from any 

manufacturing, industrial or commercial process;

iii. Tobacco smoking rooms and areas;

iv. Non-commercial food preparation;

v. General office activities, such as paper shredding, copying, photographic activities, pencil sharpening and 

blueprinting, but not including incineration;

vi. Laundry activities, except for dry-cleaning and steam boilers;

vii. Bathroom and toilet vent emissions;

viii. Fugitive emissions related to movement of passenger vehicles, if the emissions are not counted for applicability 

purposes under subsection (144)(c) of the definition of major source in this Section and any required fugitive 

dust control plan or its equivalent is submitted with the application;

ix. Use of consumer products, including hazardous substances as that term is defined in the Federal Hazardous 

Substances Act (15 U.S.C. 1261 et seq.) where the product is used at a source in the same manner as normal 

consumer use;

x. Activities directly used in the diagnosis and treatment of disease, injury or other medical condition;

xi. Circuit breakers;

xii. Adhesive use which is not related to production.

e. Storage, Piping and Packaging

i. Storage tanks, vessels, and containers holding or storing liquid substances that will not emit any VOC or HAP;

ii. Storage tanks, reservoirs, and pumping and handling equipment of any size containing soaps, vegetable oil, 

grease, animal fat, and nonvolatile aqueous salt solutions, if appropriate lids and covers are used;

iii. Chemical storage associated with water and wastewater treatment where the water is treated for consumption 

and/or use within the permitted facility;

iv. Chemical storage associated with water and wastewater treatment where the water is treated for consumption 

and/or use within the permitted facility;

v. Storage cabinets for flammable products;

vi. Natural gas pressure regulator vents, excluding venting at oil and gas production facilities;

vii. Equipment used to mix and package soaps, vegetable oil, grease, animal fat, and nonvolatile aqueous salt 

solutions, if appropriate lids and covers are used;

f. Sampling and Testing

i. Vents from continuous emissions monitors and other analyzers;

ii. Bench-scale laboratory equipment used for physical or chemical analysis, but not laboratory fume hoods or vents;

iii. Equipment used for quality control, quality assurance, or inspection purposes, including sampling equipment 

used to withdraw materials for analysis;

iv. Hydraulic and hydrostatic testing equipment;

v. Environmental chambers not using HAP gases;

vi. Soil gas sampling;

vii. Individual sampling points, analyzers, and process instrumentation, whose operation may result in emissions 

but that are not regulated as emission units;
g. Safety Activities

i. Fire suppression systems;

ii. Emergency road flares;

h. Miscellaneous Activities

i. Shock chambers;

ii. Humidity chambers;

iii. Solar simulators;

iv. Cathodic protection systems;

v. High voltage induced corona; and

vi. Filter draining.

145. “Unclassified area” means an area which the Administrator, because of a lack of adequate data, is unable to classify as 

an attainment or nonattainment area for a specific pollutant, and which, for purposes of this Chapter, is treated as an 

attainment area.

146. “Uncombined water” means condensed water containing analytical trace amounts of other chemical elements or 

compounds.

147. “Urban or suburban open area” means an unsubdivided tract of land surrounding a substantial urban development of a 

residential, industrial, or commercial nature and which, though near or within the limits of a city or town, may be 

uncultivated, used for agriculture, or lie fallow.

148. “Vacant lot” means a subdivided residential or commercial lot which contains no buildings or structures of a temporary 

or permanent nature.

149. “Vapor” means the gaseous form of a substance normally occurring in a liquid or solid state.

150. “Visibility impairment” means any humanly perceptible change in visibility (light extinction, visual range, contrast, 

coloration) from that which would have existed under natural conditions.

151. “Visible emissions” means any emissions which are visually detectable without the aid of instruments and which contain 

particulate matter.

152. “Volatile organic compounds” or “VOC” means any compound of carbon, excluding carbon monoxide, carbon dioxide, 

carbonic acid, metallic carbides or carbonates, and ammonium carbonate, that participates in atmospheric photochemical 

reactions. This includes any such organic compound other than the following:

a. Methane;

b. Ethane;

c. Methylene chloride (dichloromethane);

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);

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);

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);

qq. 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF3)2CFCF2OC2H5;

rr. Methyl acetate; and

ss. 1,1,1,2,2,3,3-heptafluoro-3-methoxypropane (n-C3F7OCH3, 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-hentafluoropropane (HFC 227ea); 

vv. Methyl formate (HCOOCH3): and

ww. (1) 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane (HFE-7300);

xx. Propylene carbonate;

yy. Dimethyl carbonate; and

zz. Perfluorocarbon compounds that fall into these classes:

i. Cyclic, branched, or linear, completely fluorinated alkanes.

ii. Cyclic, branched, or linear, completely fluorinated ethers with no unsaturations.

iii. Cycle, branched, or linear, completely fluorinated tertiary amines with no unsaturations; or

iv. Sulfur containing perfluorocarbons with no unsaturations and with sulfur bonds only to carbon and fluorine.

aaa. The following compound is VOC for purposes of all recordkeeping, emissions reporting, photochemical dispersion 

modeling and inventory requirements which apply to VOC and shall be uniquely identified in emission reports, but 

are not VOC for purposes of VOC emissions limitations or VOC content requirements: t-butyl acetate.

153. “Wood waste burner” means an incinerator designed and used exclusively for the burning of wood wastes consisting of 

wood slabs, scraps, shavings, barks, sawdust or other wood material, including those that generate steam as a by-product.

Historical Note

Former Section R9-3-101 repealed, new Section R9-3-101 adopted effective May 14, 1979 (Supp. 79-1). Amended effective 

October 2, 1979 (Supp. 79-5). Editorial correction, paragraph (133) (Supp. 80-1). Editorial correction, paragraph (58) 

(Supp. 80-2). Amended effective July 9, 1980. Amended by adding new paragraphs (24), (55), (102), and (115) and 

renumbering accordingly, effective August 29, 1980 (Supp. 80-4). Amended effective May 28, 1982 (Supp. 82-3). 

Amended effective September 22, 1983 (Supp. 83-5). Amended paragraph (133), added paragraph (156) and 

renumbered accordingly effective September 28, 1984 (Supp. 84-5). Amended paragraph (29) by deleting (aa) and (bb) 

effective August 9, 1985 (Supp. 85-4). Former Section R9-3-101 renumbered without change as R18-2-101 (Supp. 87-

3). Amended paragraph (98) effective December 1, 1988 (Supp. 88-4). Amended effective September 26, 1990 (Supp. 

90-3). Amended effective November 15, 1993 (Supp. 93-4). Amended effective June 10, 1994 (Supp. 94-2). Amended 

effective October 7, 1994 (Supp. 94-4). Amended effective February 28, 1995 (Supp. 95-1). Amended effective August 

1, 1995 (Supp. 95-3). Amended effective January 31, 1997; filed with the Office of Secretary of State January 10, 1997 

(Supp. 97-1). Amended effective June 4, 1998 (Supp. 98-2). Amended by final rulemaking at 5 A.A.R. 4074, effective 

September 22, 1999 (Supp. 99-3). Amended by final rulemaking at 8 A.A.R. 2543, effective May 24, 2002 (Supp. 02-

2). Amended by final rulemaking at 9 A.A.R. 4541, effective December 2, 2003 (Supp. 03-4). Amended by final 

rulemaking at 11 A.A.R. 3305, effective October 3, 2005 (Supp. 05-3). Amended by final rulemaking at 11 A.A.R. 

5504, effective February 4, 2006 (Supp. 05-4). Amended by final rulemaking at 12 A.A.R. 1953, effective January 1, 

2007 (Supp. 06-2). Amended by final rulemaking at 18 A.A.R. 1542, effective August 7, 2012 (Supp. 12-2).