Except as otherwise specifically provided in these rules and, except where the context otherwise indicates, words used in these rules are used in exactly the same sense as the same words are used in the Health and Safety Code.

A1 Actual Emission Reductions

A reduction in allowable emissions from the stationary source selected for emission offsets, from a baseline which is representative of normal operations approved by the Control Officer. This baseline must be based on the average of actual emissions from the three years operation immediately prior to the submission of the complete application. The Control Officer may approve any other time period, within five years prior to the date of application that is more representative of normal source operation.

A2 Affected Pollutant

An air pollutant for which an ambient air quality standard has been established by the EPA and/or the ARB and the precursors to such pollutants. Also those air pollutants which the EPA, and ARB of the District, after public hearing determine may have a significant adverse effect on the environment, public health or public welfare.

A3 Agricultural Burning

Open outdoor fires used in agricultural operations in the growing of crops or raising of fowl or animals, forest management, range improvement, wildland vegetative management, the improvement of land for wildlife and game habitat, disease or pest prevention or the maintenance of a system for delivery of water used in agricultural operations.

A4 Air Contaminant or Air Pollutant

Any discharge, release, or other propagation into the atmosphere and includes, but is not limited to, smoke, charred paper, dust, soot, grime, carbon, fumes, gases, odors, particulate matter, acids, or any combination thereof.

A5 Air Quality Increment

An increment of allowable air quality degradation, beyond baseline, as established in the Clean Air Act Section 163(b) or, for pollutants for which no increment has been established pursuant to the Clean Air Act, an increment of allowable air quality degradation as established by the District.

In establishing air quality increments, the District shall take into consideration the impact of emissions on neighboring areas.

A6 Ambient Air Quality Standards

Unless otherwise specifically stated, ambient air quality standards shall be interpreted to be federal and state ambient air quality standards. For the purpose of submittal to the Environmental Protection Agency for the inclusion in State Implementation Plan, all references in this rule are to Ambient Air Quality Standards.

A7 Approved Combustibles

Paper, cardboard, wood, dry vegetative matter or other materials as approved by the Control Officer.

A8 Atmosphere

The air that envelopes or surrounds the earth.


The California Air Resources Board.

B1 Baseline Air Quality; Date

The ambient concentration level reflecting actual air quality as monitored or modeled as of May 5, 1979.

B2 Best Available Control Technology (BACT)

For any stationary source, the more stringent of:

  1. The most effective emission control device, emission limit, or technique which has been required or used for the type of equipment comprising such stationary source, unless the applicant demonstrates to the satisfaction of the Control Officer that such limitations are not achievable; or
  2. Any other emission control device or technique determined to be technologically feasible and cost effective by the Control Officer. Under no circumstances shall BACT be determined to be less stringent than the emission control required by any applicable provision of District, State, or Federal laws or regulations, unless the applicant demonstrates to the satisfaction of the Control Officer that such limitations are not achievable.

B3 Board

The Air Pollution Control Board of the Siskiyou County Air Pollution Control District which is the Board of Supervisors.

B4 Bulk Plant

Any facility where petroleum products are received by tank car or tank vehicle and are stored or blended in bulk for the purpose of distribution in tank car or tank vehicle.

C1 Cargo Carriers

Trains dedicated to a specific stationary source.

C2 Class I Area

Any area which has been or may be designated Class I by a Federal or State authority empowered to make such designation.

C3 Class I Impact Area

All lands within the District, located within 10 kilometers of any Class I area.

C4 Cogeneration

The sequential use of energy for the production of electrical and useful thermal energy. The sequence can be thermal use followed by power production or the reverse, subject to the following standards:

  1. At least five (5) percent of the facility's total annual energy output shall be in the form of useful thermal energy.
  2. Where useful thermal energy follows power production, the thermal energy output is not less than 42.5 percent of any natural gas and oil energy input.

C5 Combustible Waste

Any solid or liquid combustible waste material containing carbon in a free or combined state.

C6 Combustion Contaminants

Particulate matter discharged into the atmosphere from the burning of any kind of material containing carbon in a free or combined state.

C7 Complete Application

Completeness of an application for an authority to construct a new or modified stationary source shall be evaluated on the basis of a list of required information shown in Appendix A of these regulations.

C8 Condensed Fumes

Minute, solid particles generated by the condensation of vapors from solid matter after volatilization from the molten state, or may be generated by sublimation, distillations, calcination, or chemical reaction, when these processes create air-borne particles.

C9 Contiguous Property

Two or more parcels of land with a common boundary or separated solely by a public roadway or other public right-of-way.

C10 Control Officer

An Air Pollution Control Officer of the Siskiyou County Air Pollution Control District.

C11 Cost-Effective

A cost per unit of emissions reduction which is lower than or equivalent to the maximum unit costs of the same emission reduction through the use of demonstrated BACT calculated in current year dollars.

D1 District

The Siskiyou County Air Pollution Control District.

D2 Dusts

Minute, solid particles released into the air by natural forces or by mechanical processes such as crushing, grinding, milling, drilling, demolishing, shoveling, conveying, covering, bagging, sweeping, or other similar processes.


The United States Environmental Protection Agency, as established by Title 40 of the Code of Federal Regulations.

F1 Federal Land Manager

The Secretary of the Department with authority over the specified federal lands.

F2 Fugitive Emissions

Emissions which could not reasonably pass through a stack, chimney, vent or other functionally equivalent opening.

G1 Good Engineering Practice

The height necessary to ensure that emissions from a stack do not result in excessive concentrations of any air contaminant in the immediate vicinity of the source.

H1 Halogenated Hydrocarbons

1,1,1-trichloroethane, methylene chloride, trichlorfluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), chlorodifluoromethane (CFC-22), trifluoromethane (CFC-23), trichlorotrifluoroethane (CFC-113), dichlorotetrafluoroethane (CFC-114), and chloropenta-fluoroethane (CFC-115).

H2 Hearing Board

The Hearing Board of the Siskiyou County Air Pollution Control District.

I1 Impact Analysis

An air quality modeling analysis used to estimate maximum ground level impacts of a source for total suspended particulates, carbon monoxide, oxides of sulfur, and oxides of nitrogen assuming one hundred (100) percent conversion of nitrogen oxides into NO2 and calculating all emissions of sulfur oxides as SO2 .

I2 Implement of Husbandry

A vehicle which is used exclusively in the conduct of agricultural operations, and which is not designed primarily for the transportation of persons or property on a highway.

I3 Incinerator

Any furnace or similar enclosed fire-chamber, with or without a draft control, used for burning refuse or other waste material.

M1 Major Source

Any stationary source which directly emits one hundred tons per year or more of any air pollutant.

M2 Modification

Any physical change, change in method of operation of, or addition to an existing stationary source, or any change in hours of operation or production rate which would necessitate a change in permit conditions, except that routine maintenance or repair shall not be considered a physical change. Unless previously limited by a permit condition, the following shall not be considered changes in method of operation:

  1. An increase in the production rate if such increase does not exceed the operating design capacity or the actual demonstrated capacity of the stationary source as approved by the Control Officer.
  2. A change in ownership.
  3. A replacement of a piece of equipment with an identical piece of equipment with emissions less than or equal to those from the original piece of equipment.

M3 Multi-Component System

A collection, or combination, of mutually dependent articles, structures, or devices customarily or necessarily started, operated and taken out of service as a unit.

M4 Multiple-Chamber Incinerator

Any article, machine, equipment, contrivance, structure, or any part of a structure used to dispose of combustible refuse by burning; consisting of three or more refractory-lined chambers in series; physically separated by refractory walls; interconnected by gas passage ports or ducts; and employing adequate design parameters necessary for maximum combustion of the material to be burned.

N1 Net Air Quality Benefit

A net improvement in air quality resulting from actual emission reductions impacting the same general area affected by the new or modified source.

N2 Net Emissions Increase

The sum of all increases in emissions of any given pollutant from a new or modified stationary source occurring after the baseline date, minus any reduction in emissions of that pollutant at the stationary source occurring five years prior to the baseline date. Reductions in emissions shall be valid for determining net emissions increases only if they are established pursuant to Authorities to Construct and Permits to Operate.

O1 Open Outdoor Fire

Complete or partial burning or smoldering of any combustible refuse or other material of any type, directly exposed to the atmosphere, whether or not enclosed in a fire-proof container, where the products of combustion are not channeled through a flue.

P1 Particulate Matter

Any material, except uncombined water, which exists in a finely divided form as a liquid or solid at standard conditions.

P2 Permit

A Certificate of Compliance, Authority to Construct, Temporary Permit to Operate, or Permit to Operate, whichever is legally in effect.

P3 Person

Any person, firm, association organization, partnership, business trust, corporation, company, contractor, supplier, installer, user or owner, or any state or local governmental agency or public district or any officer or employee thereof.

P4 PM10

Particulate matter that includes only those particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers.

P5 Portable Source

A source which has been permitted and is relocated from time to time.

P6 Potential to Emit

The maximum capacity of a stationary source to emit an air pollutant under its physical or operational design, after considering physical or operational limitations that are enforceable by permit conditions.

P7 Precursor

A directly emitted pollutant that, when released to the atmosphere, forms or causes to be formed or contributes to the formation of a secondary pollutant for which an ambient air quality standard has been adopted, or whose presence in the atmosphere will contribute to the violation of one or more ambient air quality standards.

P8 Process

For any stationary source, separate items of equipment shall be considered as part of the same process if the operation of each item of equipment is dependent upon or affects the operation of the others and the operation of all such equipment involves a common raw material or product.

P9 Process Weight

The total weight of all materials introduced into any specific process which may cause 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 weight of wood products shall be calculated at 12% moisture on a dry basis.

P10 Process Weight Rate

Total process weight divided by the number of hours in one complete operation, from the beginning to completion of any given process, excluding any time during which the equipment is idle.

P11 PSD Permit

A Permit to Operate issued pursuant to Section 105 of the Federal Clean Air Act.

R1 Reactive Organic Compound

Any volatile compound containing carbon except: methane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonates, and halogenated hydrocarbons.

R2 Reconstructed Source

Any source undergoing reconstruction where the fixed capital cost of the new components exceeds 50 percent of the fixed capital cost of a comparable entirely new stationary source. Fixed capital cost means the capital needed to provide all the depreciable components. A reconstructed source shall be treated as a new stationary source.

R3 Regulation

One of the major subdivisions of rules of the Siskiyou County Air Pollution Control District.

R4 Residential Rubbish

Refuse originating from residential uses including wood, paper, cloth, cardboard, tree trimmings, leaves, lawn clippings, and dry plants.

R5 Resource Recovery Project

A project which would convert liquid or solid waste in such a manner as to produce energy as a by-product.

R6 Rule

A rule of the Siskiyou County Air Pollution Control District.

S1 Seasonal Source

Any source with more than 75 percent of its annual emissions within a consecutive 90-day period.

S2 Section

A section of the Health and Safety Code of the State of California unless some other statute is specifically mentioned.

S3 Shall and May

"Shall" is mandatory; "May" is permissive.

S4 Significance Level

The potential of a new or modified stationary source to emit air contaminants that would equal or exceed any of the following rates:



Halogenated Hydrocarbons


Reactive Organic Compounds


Nitrogen Oxides


Sulfur Oxides


Particulate Matter


Carbon Monoxide










Vinyl Chloride




Sulfuric Acid Mist


Hydrogen Sulfide


Total Reduced Sulfur Compounds


Reduced Sulfur Compounds




Furthermore, significance level 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 an area equal to or greater than 1 microgram per cubic meter (24-hour average).

S5 Source Operation

The last operation preceding the emission of an air contaminant which operation:

  1. Results in the separation of air contaminants from the process materials or in the conversion of the process materials into air contaminants, as in the case of combustion of fuels.
  2. Is not an air pollution abatement operation.

S6 Standard Conditions

Dry gas temperature of 68 degrees Fahrenheit and dry gas pressure of 14.7 pounds per square inch absolute. Results of all analyses and tests shall be calculated and reported at this gas temperature and pressure.

S7 Stationary Source

Any building, structure, facility, or installation which emits or may emit any affected pollutant. "Building", "structure", or "facility" includes all pollutant-emitting activities, including activities located adjacent to the District boundaries which:

  1. Belong to the same industrial grouping, and
  2. Are located on one or more contiguous or adjacent properties and
  3. Are under the same or common ownership, operation, or control or which are owned or operated by entities which are under common control.

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

  1. They belong to the same two-digit standard industrial classification code, or
  2. They are part of a common production process. (Common production process includes industrial processes, manufacturing processes, and any connected processes involving a common raw material.) The emissions within District boundaries from cargo carriers dedicated to a specific stationary source, shall be considered emissions from the stationary source.

T1 Total Reduced Sulfur (TRS)

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 are not to be included in the determination of TRS.

T2 Trade Secrets

May include but not limited to any formula, plan, 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 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.

V1 Variance

An authorization by the Hearing Board to permit some act contrary to the requirements specified by these rules and regulations.

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