01/14 RULE 23: 1 

VENTURA COUNTY AIR POLLUTION CONTROL DISTRICT 

RULE 23 - EXEMPTIONS FROM PERMIT 

(Adopted 10/22/68, Revised 5/23/72, 7/18/72, 8/26/74, 3/9/76, 6/14/77, 1/17/78, 

6/20/78,11/21/78, 6/17/80, 5/5/81, 7/2/85, 10/21/86, 11/22/88, 5/16/89, 6/20/89, 6/27/89, 

9/12/89, 5/8/90, 1/8/91, 7/16/91, 1/28/92, 6/8/93, 3/22/94, 12/13/94, 7/9/96, 11/11/03, 4/13/04, 

10/12/04, 9/12/06, 4/8/08, 4/12/11, 11/12/13) 

The following operations, equipment or emission sources are exempt from the requirements of 

Rule 10, but must comply with emission standards and prohibitions. The owner or operator shall 

provide, as required by the District, calculations, usage records, emissions records and/or 

operational data as necessary to substantiate any exemptions that apply to the subject facility. 

A. Burning, Incineration, Smoke 

1. Open outdoor fires used only for recreational purposes, heating or occasional 

cooking of food for human consumption, where such use is accomplished in a 

fireplace or barbecue pit. 

2. Smoke generators that are intentionally operated for purposes of training 

observers in observing the shade or opacity of emissions. 

3. Acceptable incinerators used exclusively in connection with any structure 

designed and used exclusively as a residential dwelling for not more than four (4) 

families. (Revised 5/23/72) 

4. After July 1, 2011, safety flares rated at less than one million BTU per hour used 

exclusively used for emergency standby for the disposal of process gases in the 

event of unavoidable process upsets. (Adopted 6/14/77, Revised 4/12/11) 

B. Dust and Metalworking Fluids 

1. Material stock piles. 

2. Blasting with explosives. 

3. Mobile equipment that is used solely for the movement of solid materials. 

(Revised 5/23/72) 

4. Equipment used for buffing (except automatic or semi-automatic tire buffers), 

polishing, carving, cutting, drilling, machining, routing, sanding, sawing, surface 

grinding or turning of ceramic artwork, ceramic precision parts, leather, metals, 

plastics, rubber, fiberboard, masonry, carbon or graphite. This exemption applies 

to equipment used with metalworking fluids, direct contact lubricants, or 

vanishing oils that are Super Compliant Materials containing 50 grams ROC per 
01/14 RULE 23: 2 

liter of material or less, including, but not limited to, metal protecting (corrosion 

inhibitor application equipment) and metal treating quench tanks, except metal 

forging operations are still subject to permit requirements. 

 The following equipment using any metalworking fluid is exempt from permit 

requirements regardless of the ROC content of the fluid being used: 

 a. Lapping 

 b. Sinker Electrical Discharge Machining 

 c. Carbide grinding machine tools where the machine tool manufacturer 

specifies the viscosity of the fluid 

 d. Machining of aluminum or magnesium in single or multiple spindle 

automatic machines. 

5. Equipment used for carving, cutting, drilling, surface grinding, planing, routing, 

sanding, sawing, shredding, or turning of wood or paper, or the pressing or storing 

of sawdust, wood chips or wood shavings. 

6. Blast cleaning equipment using a suspension of abrasives in water. 

7. Abrasive blast cabinet-dust filter integral combination units where the total 

internal volume of the blast section is 50 cubic feet or less. 

8. Batch mixers of 5 cubic feet rated working capacity or less. 

9. Tumblers used for the cleaning or deburring of metal products without abrasive 

blasting. 

10. Lint traps used exclusively in conjunction with dry cleaning tumblers. 

11. Laundry dryers, extractors or tumblers used for fabrics cleaned only with water 

solutions of bleach or detergents. 

C. Heaters, Boilers 

1. Space heating and heat transfer equipment rated at less than one million BTU/s 

per hour, except reboilers that are part of a glycol dehydration unit. (Revised 

6/14/77, 12/13/94) 

2. Equipment rated at less than one million BTUs per hour and used exclusively for 

steam cleaning. (Revised 6/20/89) 

3. Natural draft hoods, natural draft stacks or natural draft ventilators. 
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D. Vehicles, Engines 

1. Vehicles, as defined by the Vehicle Code of the State of California. A vehicle 

may have an engine that both propels the vehicle and powers equipment mounted 

on the vehicle. Not included is any equipment mounted on a vehicle that would 

otherwise require a permit under the provisions of these Rules and Regulations. 

2. Locomotives, aircraft, marine vessels, and recreational watercraft used to transport 

passengers or freight. Not included is any equipment mounted on a locomotive, 

aircraft or marine vessel that would otherwise require a permit under the 

provisions of these Rules and Regulations. 

3. (Reserved) 

4. Internal combustion engines used exclusively for frost protection. 

5. (Reserved) 

6. Internal combustion engines with a maximum continuous design power rating of 

less than 50 brake horsepower and gas turbines with a rated full load output of 

less than 0.30 megawatts (300 kilowatts) at ISO Standard Day Conditions. 

7. Emergency internal combustion engines, as follows: 

a. Spark-ignited internal combustion engines used exclusively for the 

emergency pumping of water for either fire protection or flood relief. The 

engines may either drive pumps directly or generate electricity to drive 

pumps. Such engines may be operated for engine maintenance. 

b. Spark-ignited emergency internal combustion engines used only when 

electrical power line or natural gas service fails. Such engines may be 

operated for engine maintenance. 

c. Portable engines used for emergency purposes. An engine powering a 

generator connected to a facility's electrical grid in preparation for a future 

emergency shall not be considered a portable emergency engine. 

Engine maintenance operation is limited to 50 hours per calendar year per engine. 

 An emergency internal combustion engine may not be operated to replace an 

internal combustion engine or a turbine that has failed or requires maintenance; to 

supplement a primary power source when the load capacity or rating of the 

primary power source has been either reached or exceeded; nor to reduce the 

demand for electrical power when normal electrical power line service has not 

failed. 
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8. (Reserved) 

9. Portable internal combustion engines, including any turbines qualified as military 

technical support equipment under Health and Safety Code Section 41754, used 

pursuant to registration in the California Statewide Portable Engine Registration 

Program (PERP) under Health and Safety Code Section 41753. 

E. Food Preparation, Processing, Household 

1. Equipment used in connection with any structure designed and used exclusively as 

a residential dwelling. 

2. (Reserved) 

3. Vacuum cleaning systems used exclusively for industrial, commercial, 

institutional or residential housekeeping purposes.

4. Comfort air conditioning or ventilating systems which are not designed to remove 

air contaminants generated by or released from specific units of equipment. 

5. Refrigeration units except those used as, or in conjunction with, air pollution 

control operations. 

6. Smokehouses for food preparation in which the maximum horizontal inside crosssectional area does not exceed 2 square meters (21.5 square feet). 

7. Smokehouses that use liquid smoke exclusively and are completely enclosed. To 

qualify, a smokehouse must vent to neither a control device nor the atmosphere. 

8. Confection cookers where products are edible and intended for human 

consumption. 

9. Grinding, blending or packaging equipment used exclusively for tea, cocoa, 

roasted coffee, flavor, fragrance extraction, dried flowers, or spices, and control 

equipment used exclusively with such equipment, provided no organic solvents 

are used. 

10. Equipment used for the purpose of preparing food for human consumption, except 

conveyorized charbroilers and coffee roasting equipment with a maximum 

capacity of greater than 25 pounds, in either eating establishments or retail 

establishments. 

11. Equipment used to produce noodles, macaroni, pasta, food mixes or drink mixes, 

and control equipment used exclusively with such equipment, where products are 

edible and intended for human consumption, provided no organic solvents are 
01/14 RULE 23: 5 

used. Not included are storage bins located outside buildings and combustion 

equipment not exempt pursuant to Subsection C.1. 

12. Non-retail cooking kettles, excluding deep-frying equipment, where the product is 

edible and intended for human consumption. 

13. Coffee roasting equipment with a maximum capacity of 25 pounds or less. 

14. Ovens, mixers, scales, blenders used in bakeries, and control equipment used 

exclusively with such equipment, where products are edible and intended for 

human consumption and where total production is less than 1,000 pounds of 

product per operating day. 

F. Organic Compound Emissions 

1. Storage in or loading into any tank having a capacity of 550 gallons or less that is 

equipped with a submerged fill pipe and is not required to have a vapor recovery 

system. (Revised 11/22/88) 

2. Equipment for loading and storing of a reactive organic compound liquid into any 

stationary storage tank having a capability of holding 250 gallons or less. 

(Revised 5/23/72) 

3. Equipment for loading of reactive organic compound liquid into transportable 

containers of 100 gallons or less. 

4. Equipment for loading of a maximum of 500 gallons per calendar day or less of 

reactive organic compound liquid into transportable containers. 

5. Containers for the storage of unheated asphalt. (Revised 5/23/72) 

6. Nonrefillable aerosol cans. 

7. Products used for facility, grounds, and building maintenance and repair, 

including solvents, coatings, adhesives, lubricants, and sealants. Facility 

maintenance and repair does not include the use of these products for maintenance 

and repair of process and industrial equipment when this activity is being 

conducted by contractors. 

8. Janitorial services and use of products for routine janitorial maintenance, 

including graffiti removal. 

9. Office and administrative use of products such as ink, marking pens, ink pads, 

glues and adhesives, and cleaning solvents. Office and administrative use does 

not include production activities by facilities involved in graphic arts operations. 
01/14 RULE 23: 6 

10. Cleaning operations and materials as follows: 

a. Cleaning agents certified by the SCAQMD as Clean Air Solvents. 

b. Cleaning agents that contain no more than 25 grams per liter of ROC as 

used or applied, and no more than 5 percent by weight combined of 

methylene chloride, perchloroethylene, trichloroethylene, 1,1,1-

trichloroethane, carbon tetrachloride, and chloroform. 

c. Cold cleaners using non-boiling organic solvent(s) with an initial boiling 

point (excluding water) greater than 150 oC (302 oF) having a liquid 

surface area of less than 1 square meter (10.8 square feet), at any stationary 

source where less than 1000 pounds of ROC, are lost to the atmosphere 

from all such cold cleaners during every rolling period of 12 consecutive 

calendar months. 

d. Solvent cleaning operations, including cold cleaners, vapor degreasers, 

wipe cleaning, dip cleaning and flush cleaning, but excluding coating, 

graphic arts, adhesive/sealant and polyester resin operations, where less 

than 200 pounds each of ROC, methylene chloride, 1,1,1 trichloroethane, 

and perchloroethylene are lost to the atmosphere from all such activities at 

the stationary source during any rolling period of 12 consecutive calendar 

months. Emissions from activities exempted by subsections a, b, and c, 

above, shall not be included in this determination. 

11. Coating operations and materials as follows: 

a. (Reserved) 

b. Coating operations, other than motor vehicle or mobile equipment coating 

operations, where less than 200 pounds each of ROC, methylene chloride, 

1,1,1 trichloroethane, and perchloroethylene are lost to the atmosphere 

during every rolling period of 12 consecutive calendar months. 

 For the purpose of this section, coating operations shall include emissions 

from coatings, thinning, substrate surface preparation, and application 

equipment cleaning, associated with the coating operation. Emissions 

from cold cleaners and vapor degreasers shall not be included in this 

determination. Emissions included in a graphic arts operation shall not be 

included in this determination. 

c. Coatings used in mobile automotive touch-up operations where 

application is done using either a paint brush or an air brush with a cup 

that holds no more than 4 ounces of paint. 
01/14 RULE 23: 7 

12. Adhesive/sealant operations where less than 200 pounds each of ROC, methylene 

chloride, 1,1,1 trichloroethane, and perchloroethylene are lost to the atmosphere 

during every rolling period of 12 consecutive calendar months. 

For the purpose of this section, adhesive/sealant operations shall include 

emissions from adhesives, sealants, adhesive/sealant primers, thinning, substrate 

surface preparation, and application equipment cleaning, associated with the 

adhesive/sealant operation. Emissions from cold cleaners and vapor degreasers 

shall not be included in this determination. Emissions included in a graphic arts 

operation shall not be included in this determination. 

13. Graphic arts operations (including but not limited to packaging gravure, 

publication gravure, flexographic printing, screen printing, letterpress, 

lithographic printing, or ink jet printing) where less than 200 pounds each of 

ROC, methylene chloride, 1,1,1 trichloroethane, and perchloroethylene are lost to 

the atmosphere during every rolling period of 12 consecutive calendar months. 

For the purpose of this section, graphic arts operations shall include emissions 

from inks, ink additives, fountain solutions, substrate surface preparation, 

application equipment cleaning, coatings, and adhesives for binding or gluing 

printed substrates, associated with the graphic arts operation. Emissions from 

cold cleaners and vapor degreasers shall not be included in this determination. 

14. Polyester resin operations using less than 240 gallons of polyester resin materials 

over a rolling period of 12 consecutive calendar months, including unsaturated 

polyester resins, cross-linking agents, catalysts, gel coats, inhibitors, accelerators, 

promoters, and any other material containing ROC and used in the polyester resin 

operation. Inert filler and cleaning material is specifically excluded from this 

determination. 

15. Operations using organic solvent (other than solvent cleaning operations, coating 

operations, adhesive operations, graphic arts operations, polyester resin 

operations, semiconductor manufacturing, dry cleaning, and other defined 

exempted uses) that emit less than 200 pounds each of ROC, methylene chloride, 

1,1,1 trichloroethane, and perchloroethylene during every rolling period of 12 

consecutive calendar months. 

16. Equipment for melting and applying coatings of oils, waxes, greases, resins, and 

like substances where no reactive organic solvents, diluents or thinners are used. 

17. Equipment used exclusively for the manufacture of water emulsions of asphalt, 

greases, oils or waxes or the manufacture of waterbased adhesives or waterbased 

paints. 
01/14 RULE 23: 8 

18. Equipment used to compress, store, liquefy or separate gases from the air or to 

compress or store natural hydrocarbon gases, other than engines. (Revised 

5/23/72) 

19. Equipment used exclusively to mill or grind coatings and molding compounds 

where all materials charged are in a paste form. 

20. Oilfield wastewater sumps, pits or ponds, where the ROC content of the 

wastewater entering the sump, pit or pond is less than 5 milligrams per liter. 

21. Any tank or container used to hold or store reactive organic compound liquids, 

except gasoline and crude oil, that is not required to have reactive organic 

compound vapor emission controls. 

22. (Reserved) 

23. Any soil aeration project exempt from the soil aeration limit in Rule 74.29 

pursuant to Subsection C.1 or C.2 of Rule 74.29. This exemption applies only to 

soils contaminated with gasoline, diesel fuel or jet fuel. 

24. Any soil remediation project where collected organic vapors are not emitted to the 

atmosphere by any means. For the purpose of this subsection, this may include, 

but is not limited to, routing the vapors into the ground. 

G. Experimental Operations 

Bench scale experimental or research operations and equipment used exclusively for 

investigation, experimentation or research to advance the state of air pollution control 

knowledge or to improve techniques. This exemption is subject to express prior approval 

from the Air Pollution Control Officer and shall include a time limitation. (Revised 

5/23/72, 4/13/04) 

H. Plastics and Rubber 

1. Presses used for the curing of rubber products and plastic products. 

2. Ovens used exclusively for the curing of plastics that are concurrently being 

vacuum held to a mold or for the softening or annealing of plastics. 

3. Equipment used for compression molding or injection moulding of plastics. 

4. Mixers for rubber or plastics where no material in powder form is added and no 

organic solvents, diluents or thinners are used. 

5. Ovens used exclusively for the curing of vinyl plastisols by the closed mold 

curing process. 
01/14 RULE 23: 9 

6. Roll mills or calendar for rubber or plastics where no organic solvents, diluents or 

thinners are used. 

7. Ovens used exclusively for curing potting materials or castings made with epoxy 

resins. 

8. Equipment used exclusively for conveying and storing plastic pellets. 

9. Presses used exclusively for extruding plastics where no heat is applied. 

I. Metals and Ceramics 

1. Porcelain enameling furnaces, porcelain enameling drying ovens, vitreous 

enameling furnaces or vitreous enameling drying ovens of one million BTU/s per 

hour or less heat input. (Revised 5/23/72) 

2. Kilns used for firing ceramic ware of one million BTU/s per hour or less heat 

input. (Revised 6/14/77) 

3. Equipment used exclusively for heat treating or sintering glass or metals or for 

case hardening metals of one million BTU/s per hour or less heat input. (Revised 

5/23/72) 

4. Presses used exclusively for extruding metals, minerals or wood where no heat is 

applied. 

5. Equipment used for hydraulic or hydrostatic testing. 

6. Equipment used for inspection of metal products.

7. Brazing, soldering or welding equipment. 

8. Molds used for the casting of metals. 

9. Equipment using dilute aqueous solutions for surface preparation, cleaning, 

stripping, etching (does not include chemical milling) or the electrolytic plating, 

electrolytic polishing or the electrolytic stripping of brass, bronze, cadmium, 

copper, iron, lead, nickel, tin, and zinc. This exemption does not apply to chrome 

plating or chromic acid anodizing. (Revised 5/23/72, 6/27/89) 

10. Equipment used for washing or drying products fabricated from metal or glass, 

provided that no volatile organic materials are used in the process and that no oil 

or solid fuel is burned. 
01/14 RULE 23: 10 

11. Crucible furnaces, pot furnaces, or induction furnaces, with a capacity of 1000 

pounds or less each with fail-safe temperature controllers preventing vapor boiloff, in which no sweating or distilling is conducted and from which only the 

following metals are poured or in which only the following metals are held in a 

molten state. (Revised 5/23/72) 

a. Aluminum or any alloy containing over 50 percent aluminum. 

b. Magnesium or any alloy containing over 50 percent magnesium. 

c. Lead or any alloy containing over 50 percent lead. 

d. Tin or any alloy containing over 50 percent tin.

e. Zinc or any alloy containing over 50 percent zinc. 

f. Copper 

g. Precious metals 

12. Crucible furnaces, pot furnaces or induction furnaces with a brimful capacity of 

less than 450 cubic inches of any molten metal. (Revised 6/14/77) 

13. Wax burnout kilns with an internal volume of 0.2 cubic meters (7.0 cubic feet) or 

less and a rated capacity of less than one million BTUs per hour. 

J. Miscellaneous 

1. Bench scale laboratory equipment used exclusively for chemical or physical 

analyses or experiments. (Revised 6/14/77) 

2. Vacuum producing devices in laboratory operations or in connection with other 

equipment that is exempt by this Rule. 

3. Fuel cells that use phosphoric acid, molten carbonate, proton exchange membrane 

or solid oxide technologies. 

4. Photographic process equipment by which an image is reproduced upon material 

sensitized to radiant energy. 

5. Equipment used exclusively to package pharmaceuticals or cosmetics or to coat 

pharmaceutical tablets. 

6. Shell-core and shell-mold manufacturing machines. 
01/14 RULE 23: 11 

7. Die casting machines. 

8. Equipment used exclusively for bonding lining to brake shoes. 

9. Valves and flanges. 

10. Cooling towers and ponds that are not in contact with contaminated process water. 

11. Equipment used exclusively for the dyeing or stripping (bleaching) of textiles 

where no organic solvents, diluents, thinners or sulfur compounds are used. 

12. Any article, machine, equipment, contrivance or their exhaust systems, the 

discharge from which contains airborne radioactive materials and which is emitted 

into the atmosphere in concentrations above the natural radioactive background 

concentration in air. "Air-borne radioactive material" means any radioactive 

material dispersed in the air in the form of dusts, fumes, smoke, mists, liquids, 

vapors or gases. 

Nuclear energy development and radiation protection are controlled by the State 

of California, to the extent it has jurisdiction thereof, by the California Energy 

Commission and the California Department of Health Services. Such 

development and protection are fully regulated by the United States Nuclear 

Regulatory Commission to the extent that such authority has not been delegated to 

the states. 

13. Repairs, including the replacement of worn or defective parts, to any article, 

machine, equipment or other contrivance where a Permit to Operate had 

previously been granted for such equipment, so long as such repairs do not 

constitute a substantial replacement of the equipment as a whole. (Revised 

1/17/78) 

14. Any sterilizer or aerator at a stationary source where the amount of ethylene oxide 

charged to all sterilizers at the stationary source is no more than 4 pounds per year 

(lb/yr). 

15. Equipment used exclusively to generate ozone and associated ozone destruction 

equipment for the treatment of cooling tower water or for water treatment 

processes. 

16. Emission units used exclusively in agricultural operations, except where the total 

actual annual emissions, excluding fugitive PM10 emissions, from an agricultural 

source is equal to or greater than 50 percent of any of the following federal major 

source thresholds: 

Pollutant Threshold (Tons Per Year) 
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Any single HAP 10 

Combination of HAPs 25 

CO, PM10, or SOx 100 

Greenhouse Gases (CO2e)(effective July 1, 2011) 100,000 

Greenhouse Gases (CO2e)(until July 1, 2011) No Applicable Threshold 

Attainment / Nonattainment Threshold (TPY) 

 Classification (Ozone) (ROC, NOx) 

Attainment, Marginal, or Moderate 100 

Serious 50 

Severe 25 

Extreme 10 

This provision shall not exempt any large confined animal facility or any major 

source or any major modification to a major source required to be issued a permit 

pursuant to Title I (42 U.S.C. Sec. 7401 et seq.) or Title V (42 U.S.C. Sec. 7661 et 

seq.) For the purpose of this subsection, agricultural operations are operations 

conducted in the raising of fowl or animals or the production of products of the 

soil, including crops, orchard fruits, trees, vines, rose bushes, ornamental plants, 

floricultural crops, and other horticultural crops. An agricultural source includes 

all emissions units that are not exempt pursuant to other provisions of this rule 

which are used in agricultural operations located on contiguous property under 

common ownership or control. 

For the purpose of this subsection a “large confined animal facility” is defined as 

follows: 

(i) 1,000 milk-producing dairy cows; 

(ii) 3,500 beef cattle; 

(iii) 7,500 calves, heifers or other cattle; 

(iv) 650,000 chickens other than laying hens; 

(v) 650,000 laying hens; 

(vi) 650,000 ducks; 

(vii) 100,000 turkeys; 

(viii) 3,000 swine; 

(ix) 2,500 horses; 

(x) 15,000 sheep, lambs, or goats; or 

(xi) 30,000 rabbits or other animals. 

[Source: CCR Title 17, Division 1, Chapter 1, Subchapter 2.7, §86500(a)]