RULE 130 - DEFINITIONS

Except as otherwise specifically provided in these rules and 

regulations, and except where the context indicates otherwise, 

words used in these rules and regulations are used in exactly 

the same sense as the same words are used in the Health and 

Safety Code of the State of California, the Clean Air Act of 

1977, and the Code of Federal Regulations 40 CFR 52.21 (August 

7, 1980). Where the federal regulations of 40 CFR 52.21 refer 

to the responsibilities of the administrator of the U.S. 

Environmental Protection Agency, the term Administrator shall be 

construed to mean Control Officer. 

(a1) AGRICULTURAL OPERATION: The growing and harvesting of 

crops, or the raising of fowl, animals or bees as a gainful 

occupation, or forest management, or range improvement or in the 

improvement of land for wildlife and game habitat, or disease or 

pest prevention. 

(a2) AIR CONTAMINANT: Any discharge, release, or other 

propagation into the atmosphere directly, or indirectly, caused 

by man and includes, but is not limited to, smoke, charred 

paper, dust, soot, grime, carbon, fumes, gases, odors, 

particulate matter, acid, or any combination thereof. 

(a3) AIR POLLUTION ABATEMENT OPERATION: Any operation which has 

as its essential purpose a significant reduction in the emission 

of air contaminants or the effect of such emission. 

(a4) AMBIENT AIR QUALITY STANDARD: The specific concentrations 

and durations of air pollutants which reflect the relationship 

between intensity and composition of pollution to undesirable 

effects. 

(a5) APPROVED COMBUSTIBLES: Paper, cardboard, brush, trees, 

native vegetation or other materials as approved by the Control 

Officer. 

(b1) BASELINE CONCENTRATION: That ambient concentration level 

which exists in the baseline area at the time of the 

establishment of the applicable baseline date as determined in 

accordance with Section 52.21 of the Code of Federal 

Regulations. (52.21(b)(13)) 

(b2) BASE UNIT: Any major emitting device, process line, or 

other equipment or grouping thereof, that emits, or has the 

potential to emit, regulated air pollutants; for the purposes of 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
this rule, the term base unit shall include, but shall not be 

limited to, any of the following: 

1) any major emitting device or process line, or 

2) any aggregate production line, including a primary 

crusher and associated crushers, screens, conveyors, 

stackers, and piles, or 

3) any cement batch plant, or 

4) any asphalt hot mix plant, or 

5) any debarker and head rig, or 

6) any rip and gangsaw line, or 

7) any planing operation, or 

8) any cooling tower, or 

9) any vent gas treatment system, or 

10) any burner/scrubber system, or 

11) any stretford system, or 

12) any geothermal production, injection, observation, or 

idle steam well and geothermal steam transmission 

system, or aggregation thereof, that provide steam to 

- or are included in the steamfield of a single or 

dual-unit geothermal electrical power generation 

plant, or 

13) any onsite combustion device used for power or process 

heat generation, except for emergency standby 

generators or any device that is covered under another 

base unit definition in this rule. 

14) any geothermal well drilling operation, or aggregation 

thereof, conducted on a company’s leasehold. 

(b3) BEST AVAILABLE CONTROL TECHNOLOGY (BACT): An emission 

limitation based on the maximum degree of reduction of each air 

contaminant subject to regulation under the Clean Air Act of 

1977 emitted from or which results from any stationary source or 

modification, which the Control Officer, on a case by case 

basis, taking into account energy, environmental, and economic 

impacts and other costs, determines is achievable for such 

stationary source through application of production processes 

and available methods, systems, and techniques for control of 

such air contaminants. Said BACT determinations may include a 

design standard, operational equipment specifications, fuel 

restrictions, work practice or combination thereof. In no event 

shall application of BACT result in emissions of any pollutants 

which will exceed the emissions allowed under Rules 490 and 492 

of this regulation. If the reviewing authority determines that 

technological or economic limitations on the application of 

measurement methodology to a particular emissions unit would 

make the imposition of an emissions standard infeasible, a 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
design, equipment, work practice, operational standard or 

combination thereof, may be prescribed instead to satisfy the 

requirements for the application of BACT. (52.21(b)(12)) 

(c1) COMBUSTION CONTAMINANTS: Matter discharged into the 

atmosphere from the burning of any kind of material, excluding 

carbon dioxide and water. 

(c2) CONTROL OFFICER: The Air Pollution Control Officer of the 

District.

(c3) CONTROL STRATEGY: A combination of measures designed to 

reduce air contaminant emissions in accordance with the State 

Implementation Plan for the California North Coast Air Basin. 

(d1) DISTRICT: The County Air Pollution Control District as 

required by Section 40002 of the California Health and Safety 

Code or a multi- county unified district authorized by Chapter 

3, Part 3, Division 26 of said code. 

(d2) DUST: Minute solid particles released into the air by 

natural forces or by mechanical processes such as crushing, 

grinding, milling, drilling, demolishing, shoveling, conveying, 

bagging, sweeping, etc 

(e1) EMISSION: The act of passing into the atmosphere an air 

contaminant or gas stream which contains an air contaminant, or 

the air contaminant so passed into the atmosphere. 

(e2) EPISODE ALERT: A condition in an air basin whenever the 

concentration of any air contaminant in that air basin has been 

verified to have reached a predetermined level which threatens 

the ambient air quality standard as defined in Rule 160 

depending upon the particular topography and meteorology of the 

air basin. "Verified" means the pertinent measuring instrument 

has been checked over the following fifteen-minute period and 

found to be operating correctly. 

(g1) GEOTHERMAL OPERATIONS: Those activities related to the 

extraction, transmission, and utilization of geothermal steam 

which may directly, or indirectly, result in air contaminant 

emissions.

(g2) GREENHOUSE GASES (GHGs): A gas that has the capacity to 

create a warming effect in the earth’s atmosphere; for the 

purposes of this rule: carbon dioxide (CO2), nitrous oxide 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
(N2O), methane (CH4), hydrofluorocarbons (HFCs), 

perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

(h1) HEARING BOARD: The appellate review board of the District 

as provided for by Section 40800 of the California Health and 

Safety Code. 

(i1) INDIRECT SOURCE: A facility, building, structure or 

installation, or combination thereof, which indirectly results 

in emissions of an air contaminant as a result of traffic 

greater than 20,000 or more vehicles per day within 10 years of 

construction; any new or modified facility which provides in 

excess of 1,000 new parking spaces; or any new or modified 

airport with more than 50,000 operations per year by regularly 

scheduled air carriers, or used by 1,600,000 or more passengers 

per year. 

(i2) INSTALLATION: The placement, assemblage or construction 

of equipment or control apparatus at the premises where the 

equipment or control apparatus will be used, and includes all 

preparatory work at such premises 

(k1) KRAFT PULP MILL: Any industrial operation which uses for 

a cooking liquor an alkaline sulfide solution containing sodium 

sulfide in its pulping process. 

(k2) KRAFT PULP-MILL NON-CONDENSIBLES: The TRS portion of any 

gases and vapors released in a kraft pulp mill from the digester 

flash steam condensers, blow tanks, multiple effect evaporator 

vacuum seal tanks, multiple effect evaporator condensers, and 

condensate strippers. 

(k3) KRAFT PULP MILL PRODUCTION: Tons of air-dried unbleached 

kraft pulp produced by a kraft pulp mill, or equivalent. A 

value equal to 50 percent of the weight of dry wood charged into 

the kraft cooking process may be substituted for those mills 

where a value of air-dried unbleached kraft pulp is not readily 

obtainable. 

(k4) KRAFT RECOVERY FURNACE: The combustion device in which 

pulping chemicals are converted to a molten smelt and wood 

solids are incinerated. For these regulations, and where 

present, this term shall include the direct contact evaporator. 

(l1) LIME KILN: Any production device in which calcium 

carbonate is thermally converted to calcium oxide. 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
(m1) MODELING: A procedure for estimating the ambient air 

concentration of air contaminants based upon emission profiles, 

dispersion simulations or other techniques approved by the 

Environmental Protection Agency, California Air Resources Board 

and the Control Officer. (52.21(l)) 

(m2) MODIFICATION: Any physical change in, or in the method of 

operation of any stationary source which increases the amount of 

any air contaminant emitted into the atmosphere by that source. 

(n1) NET INCREASE IN EMISSIONS: The amount by which the sum of 

any increase in actual emissions from a particular physical 

change or change in method of operation at a stationary source, 

and any other increases and decreases in actual emissions at the 

source that are creditable in accordance with 40 CFR 52.21(b)(3) 

and (21), exceeds zero. 

(o1) OPERATION: Any physical action resulting in a change in 

the location, form or physical properties of a material, or any 

chemical action resulting in a change in the chemical 

composition or the chemical or physical properties of a 

material. 

(o2) ORCHARD,VINEYARD, OR CITRUS GROVE HEATER: Any article, 

machine, equipment or other contrivance, burning any type of 

fuel or material capable of emitting air contaminants, used or 

capable of being used for the purpose of giving protection from 

frost damage. 

(o3) ORGANIC GAS: Any gas containing carbon and hydrogen, or 

carbon and hydrogen in combination with any other element. 

(o4) OTHER KRAFT MILL SOURCES: Sources of TRS emissions in a 

kraft mill other than recovery furnaces and lime kilns, 

including but not limited to: vents from knotters, brown stock 

washers, smelt tanks, black liquor oxidation systems, tall oil 

recovery operations, and any other vent which contributes over 1 

percent of the total kraft mill TRS emissions. 

(o5) OWNER: Includes, but is not limited to, any person who 

leases, supervises or operates equipment, in addition to the 

normal meaning of ownership. 

(p1) PARTICULATE MATTER: Any material, except uncombined 

water, which exists in a finely divided form as a liquid or 

solid at standard conditions. Specific size fractions of 

particulate matter are defined as follows:

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
PM2.5 means particulate matter, both filterable and condensable, 

with an aerodynamic diameter less than or equal to a nominal two 

and one half (2.5) micrometers.

PM10 means particulate matter, both filterable and condensable, 

with an aerodynamic diameter less than or equal to a nominal ten 

(10) micrometers.

(p2) PERMIT: Refers to either an authority to construct, 

temporary permit to operate or permit to operate, whichever is 

legally in effect. For purposes of prevention of significant 

deterioration enforceability, the permit to operate will be 

considered a modified authority to construct. 

(p3) PERSON OR PERSONS: An individual, public or private 

corporation, political subdivision, agency, board, department or 

bureau of the state, municipality, partnership, copartnership, 

firm, association, trust or estate, or any other legal entity 

whatsoever which is recognized in law as the subject of rights 

and duties. 

(p4) POTENTIAL TO EMIT: The maximum capacity of a stationary 

source to emit an air contaminant under its physical and 

operational design, after considering physical and operational 

limitations that are enforceable by conditions imposed by the 

district in both the Authority to Construct and Permit to 

Operate. (52.21(b)(4)) 

(p5) PPM: Parts per million by volume expressed on a dry gas 

basis. 

(p6) PRECURSOR: A substance that, when released to the 

atmosphere, forms or causes to be formed or contributes to the 

formation of another or secondary air pollutant for which a 

national ambient air quality standard has been adopted, or 

whose presence in the atmosphere will contribute to the 

violation of one or more national ambient air quality standards. 

Presently identified precursors and secondary pollutants are: 

 PRESCURSORS SECONDARY POLLUTANTS 

Volatile Organic Compounds Photochemical oxidants (Ozone)

 Organic fraction of PM10 

Nitrogen Oxides (NOx) Photochemical oxidants (Ozone)

 Nitrogen dioxide (NO2) 

 Nitrate fraction of PM10 

 Nitrate fraction of PM2.5

Sulfur Oxides (SOx) Sulfur dioxide (SO2) 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
 Sulfates (SO4) 

 Sulfate fraction of PM10 

 Sulfate fraction of PM2.5

(p7) PREVENTION OF SIGNIFICANT DETERIORATION (PSD) INCREMENT: 

The maximum allowable increase of ambient air quality above 

baseline concentration in the three classified areas. 

 ALLOWABLE PSD INCREMENTS 

 micrograms per cubic meter

 Class I Class II Class III 

Sulfur Dioxide 

 annual arithmetic mean 2 20 40 

 24-hour maximum* 5 91 182 

 3-hour maximum* 25 512 700 

Total Suspended Particulate Matter (PM10)

 annual geometric arithmetic mean 54 1917 

3734

 24-hour maximum* 108 3730 7560

Particulate Matter (PM2.5)

 annual arithmetic mean 1 4 8

 24-hour maximum* 2 9 18

Nitrogen Dioxide 

 Annual arithmetic mean average 2.5 25 

50 

* Not to be exceeded more than once a year. 

(p8) PROCESS WEIGHT PER HOUR: The total weight, including 

contained moisture of all materials introduced into any specific 

process which process may cause any discharge into the 

atmosphere. Solid fuels charged will be considered as part of 

the process weight, but liquid and gaseous fuels and combustion 

air will not. The "process weight per hour" will be derived by 

dividing the total process weight by the number of hours in one 

complete operation from the beginning of any given process to 

the completion thereof, excluding any time during which the 

equipment is idle. For continuous processes, the average hourly 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
total weight of materials introduced into the process will be 

used in calculations. 

s1) SECTION: Refers to a section of the Health and Safety Code 

of the State of California unless some other statute is 

specifically mentioned. 

(s2) SIGNIFICANT: The potential of a new or modified 

stationary source to emit air contaminants that would equal or 

exceed any of the following rates: (52.21(b)(23)(i)) 

Air Contaminant: Significant Emission Rate

Carbon monoxide: 100 tons per year (tpy) 

Nitrogen oxide: 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.

Ozone: 40 tpy of volatile 

 organic compounds or 

nitrogen oxides

Lead: 0.6 tpy 

Asbestos: 0.007 tpy 

Beryllium: 0.0004 tpy 

Mercury: 0.1 tpy 

Vinyl chloride: 1 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 combustors:

Organic emissions: 3.2 × 10-6 megagrams per year

(3.5 × 10-6 tons per year)

(measured as total tetrathrough octa-chlorinated 

dibenzo-p-dioxins and 

dibenzofurans) 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
Metals emissions: 14 megagrams per year (15 

tons per year) (measured as

particulate matter)

Acid gas emissions: 36 megagrams per year (40 

tons per year) (measured as 

sulfur dioxide and hydrogen 

chloride) 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
Municipal solid waste landfills:

Nonmethane organic compounds: 45 megagrams per year (50 

tons per year)

Greenhouse Gases:

For the purpose of Rule 220 only: as specified in Rule 

221.4.1 or 221.4.3

For the purpose of Regulation 5 only: as specified in Rule 

221.4.2 

Other pollutants regulated under the Clean Air Act of 1977: 

any emissions rate whatsoever (52.21(b)(23)(ii)). 

Not withstanding the above significant emission rates for 

various air contaminants, significant also means any net 

emission increase from any new or modified stationary source 

which would be constructed within 10 kilometers of a Class I 

area and have an air quality impact on such area equal to or 

greater than 1 microgram per cubic meter (24 hour 

average).(52.21(b)(23)(iii)) 

(s3) SMALL BUSINESS: (1) Any business activity in 

agriculture, general construction, special trade construction, 

retail trade, wholesale trade, services, transportation and 

warehousing, manufacturing, generation and transmission of 

electric power, or a health care facility, unless excluded in 

paragraph (2), that is both of the following: 

A. Independently owned and operated, and 

B. Not dominant in its field of operation. 

 (2) “Small business” does not include the following 

professional business activities: 

A. A financial institution or bank, a trust, a savings 

and loan association, a thrift institution, a consumer 

finance company, a commercial finance company, an 

industrial finance company, a credit union, a mortgage 

and investment banker, a securities broker-dealer, or 

an investment adviser. 

B. An insurance company, either stock or mutual. 

C. A mineral, oil, or gas broker; a subdivider or 

developer. 

D. A landscape architect, an architect, or a building 

designer. 

E. An entity organized as a nonprofit institution. 

F. An entertainment activity or production, including a 

motion picture, a stage performance, a television or 

radio station, or a production company. 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
G. A utility, a water company, or a power transmission 

company generating and transmitting more than 4.5 

million kilowatt hours annually. 

H. A petroleum producer, a natural gas producer, a 

refiner, or a pipeline. 

I. A business activity exceeding the following annual 

gross receipts in the categories of: 

(i) Agriculture, one million dollars ($1,000,000). 

(ii) General construction, nine million five hundred 

thousand dollars ($9,500,000). 

(iii) Special trade construction, five million dollars 

($5,000,000). 

(iv) Retail trade, two million dollars ($2,000,000). 

(v) Wholesale trade, nine million five hundred thousand 

dollars ($9,500,000). 

(vi) Services, two million dollars ($2,000,000). 

(vii) Transportation and warehousing, one million five 

hundred thousand dollars ($1,500,000). 

J. A manufacturing enterprise exceeding 250 employees. 

K. A health care facility exceeding 150 beds or one 

million five hundred thousand dollars ($1,500,000) in 

annual gross receipts. 

Ref: State Government Code § 11342(h) 

(s4) SMELT DISSOLVING TANK: A vessel used for dissolving the 

molten salts (smelt) recovered from the kraft recovery furnace. 

(s5) STACKING: The venting of geothermal steam from associated 

unit steam supply transmission line into the atmosphere during 

associated power plant shutdowns (outages), startups or load 

curtailments. 

(s6) STANDARD CONDITIONS: As used in these regulations, refers 

to a gas temperature of 20 degrees Centigrade (68 degrees 

Fahrenheit) and a gas pressure of 760 millimeters of mercury 

absolute (14.7 pounds per square inch absolute). 

(s7) STANDARD CUBIC METER OF GAS (STANDARD CUBIC FOOT OF GAS): 

The amount of gas that would occupy the specified cubic measure, 

if free of combined water, at standard conditions. 

(s8) STATIONARY SOURCE: All units of air contaminant emitting 

articles, machines, equipment or other contrivances, which are 

located on adjacent or contiguous properties under the control 

of the same person (or persons under common control) and all of 

which are determined by the Control Officer to be related to one 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)
another through a similar product, raw material or function and 

are included in the same standard industrial classification. 

(s9) STEAM GENERATING UNIT: Any furnace or boiler used in the 

process of burning fuel for the purpose of producing steam by 

heat transfer. 

(t1) TOTAL REDUCED SULFUR (TRS): "TRS" means total reduced 

sulfur contained in hydrogen sulfide, mercaptans, dimethyl 

sulfide, dimethyl disulfide or other organic sulfide compounds, 

all expressed as hydrogen sulfide. Sulfur dioxide, sulfur 

trioxide, or sulfuric acid mist, are not to be included in the 

determination of TRS. 

(t2) TOXIC AIR CONTAMINANT (TAC): A toxic air contaminant 

(TAC) is any substance identified by the Air Resources Board as 

a toxic air contaminant pursuant to California Health and Safety 

Code Section 39650 et. seq. 

(t3) TRADE SECRETS: As used in these rules and regulations, 

Trade Secrets include, but are not limited to, any formula, 

pattern, process, tool, mechanism, compound, procedure, 

production data, or compilation of information which is not 

patented, which is known only to certain individuals within a 

commercial concern who are using it to fabricate, produce, or 

compound an article of trade or to perform a service having 

commercial value, and which gives its user an opportunity to 

obtain a business advantage over competitors who do not know or 

use it. 

Northern Sonoma County 

Air Pollution Control District

Rule 130 (Definitions): Amended December 14, 2010 

(Last Amended July 25, 1995)