Spokane Clean Air consults during a source inspection.

Marijuana Operations

Marijuana Producers & Processors

To minimize odors and other air contaminants from marijuana production and processing operations, Spokane Regional Clean Air Agency adopted Article VI, Section 6.18Standards for Marijuana Production and Marijuana Processing, in January 2018.

Requirements that apply to all marijuana operations

  • Notification – SRCAA must be notified of any changes in operations, business closure, change of ownership, and/or name change. We recommend you contact us before considering an expansion and/or relocation, to discuss what requirements apply to your facility.
  • Operations & Maintenance Plans must be followed for air pollution control equipment.
  • Equipment – prior to installing and/or modifying equipment (e.g. generator, boiler, extraction equipment, etc.) a Notice of Construction permit may be required. Call us and ask to speak with an engineer for more information.
  • Odor Regulation – all facilities must meet the odor requirements of Article VI, Section 6.04.
  • Outdoor Burning – burning waste, including plant waste, is not allowed per Article VI, Section 6.01.

Requirements by type of operation

Producers propagate, grow, harvest, and trim marijuana to be processed. Below are requirements for each of the three categories of producers: indoor, outdoor, and other.  Processors are operations that dry, cure, extract compounds, convert, package, and/or label usable marijuana and marijuana concentrates.

Indoor Producer

Indoor Producers are operations in fully-enclosed buildings that are permanently affixed to the ground, with permanent rigid walls, non-retractable roofs, and doors. The buildings are equipped to maintain control of environmental conditions. 

Additional requirements for Indoor Producers:

  • Use air pollution control equipment, facility design, or both to reduce air contaminants.
  • Keep doors and windows closed, except for active ingress and egress. 

Outdoor Producer

Outdoor Producers are operations on an expanse of open or cleared ground (no structures of any kind) that operate during Spokane County’s customary outdoor growing season, without controlling environmental conditions. Watering and short term covering of plants for a portion of each day as needed for frost protection are not considered controlling environmental conditions. 

Outdoor producers may temporarily cover marijuana plants to protect plants from frost. Frost protection is only allowed when there is a threat of frost, the temporary cover may be placed at sunset or within two (2) hours of the expected frost occurrence. When the threat of frost has passed, the temporary cover must be removed.  

Additional requirements for Outdoor producers:

  • For indoor propagation, use air pollution control equipment, facility design, or both to reduce air contaminants.
  • Complete and submit the Harvest Schedule Notification form, no later than 30 days prior to the start of harvest. While it is impossible to know the exact harvest date(s) 30 days in advance, the expectation is to provide a window of likely “harvest date(s)” rather than a specific date. Determining your harvest schedule 30 days in advance: Producers should know 1) growth cycle of their plants, 2) stage at which to harvest to achieve desired work product characteristics, 3) timing for the harvest workforce, and 4) product availability dates to meet customer needs. As a result of these operational business needs, determining and reporting a “harvest date window” at least 30 days in advance is reasonable.

Other Producer

Other Producers are operations that do not meet the indoor producer or outdoor producer definitions. These include hoop houses and temporary or other similar structures.

Additional requirements for Other Producers:

  • Have an existing written exemption from SRCAA. Exemptions were granted as a one-time option for those who applied for such exemption by November 5, 2018.
  • Comply with the specific conditions of your exemption.
  • New or expansion of existing structures are not allowed.


Processors are operations that dry, cure, perform extraction, convert, package, and/or label usable marijuana and marijuana concentrates.

Additional requirements for Processors:

  • All processing must occur indoors.
  • Use air pollution control equipment, facility design, or both. 
  • Keep doors and windows closed except for active ingress or egress. 

Annual Registration

As of March 9, 2023, most marijuana producers and processors will not be required to register. Annual registration is required for:

  • A source with operations or equipment (e.g. a boiler) listed in Article IV, Section 4.04, that requires a Notice of Construction permit.
  • A source as determined by SRCAA’s Control Officer, per Article IV, Section 4.04 (A)(2)(c).

Registration fee information is provided in Article X, Sections 10.06, 10.15, and the Consolidated Fee Schedule, Sections 10.06, 10.15

Site Visits, Complaint Response

Our inspectors may inspect businesses to verify operational information and compliance with air quality requirements. Inspectors also respond to citizen complaints about dust, smoke, odors, and other air quality concerns.

Agricultural Exemption Applicability

Operations that meet all of the conditions of RCW 70.A.15.45.30 for an agricultural operation are not exempt from all SRCAA regulations. If an odor or fugitive dust violation is documented at an operation, the applicability of the agricultural exemption is determined at that time.

Potential Odor, Emission Control Measures

Indoor Producers and Processors

The following controls and practices have been employed alone or in combination at some marijuana production and processing operations. Control equipment must be properly-sized for the amount of airflow being treated. An Operations & Maintenance Plan must be in place for control measures being used.

Carbon adsorption filtration – Vent all air exhausted from the operation through a properly-sized carbon adsorption canister or carbon filter. The canister or filter should be sized properly for the amount of exhaust air flow. Vent room air through floor mounted carbon adsorption canisters which then exhaust back into the room.

Vertical stack exhausts indoor air to the outside with an unobstructed upward air flow. The top of the stack should be above the point of roof penetration or above the adjacent roof line.

Building configuration – Structure design has been used to eliminate the need to exhaust contaminated air directly outside. An example is a “room-within-a-room” design. This consists of completely separate production and processing rooms within a large building. Air is recirculated within the room instead of exhausting directly to the outside air.

Other possible control technologies include ozone treatment or negative ion generation.

Outdoor Operations

Potential strategies include but are not limited to:

  • Locate operation as far away as possible from the property line. This may improve air contaminant dispersion and decrease odor concentrations at and beyond the property line.
  • Move indoors when performing trimming, pruning or harvesting of plants grown in moveable containers.
  • Think in small increments or staging. For example, trim, prune or harvest small groups of plants at a time.
  • Perform trimming, pruning or harvesting when they are least likely to have off-site impacts, such as: 

    When weather conditions help disperse odors more readily. Avoid evenings and early mornings when temperature inversions are more likely to occur. Inversions inhibit air pollutants from dispersing.

    When nearby properties are least likely to be occupied. For example, in a business zone it may be weekends and evenings. In a residential area it may be week days versus evenings or weekends.
  • Keep plant height below fence height.
  • Vegetative environmental buffers (VEBs), when used in conjunction with other odor management techniques, have demonstrated some effect in reducing downwind odors from poultry and livestock operations.

    Many variables influence the effectiveness of a VEB including weather, topography, wind, type and size of plants in the VEB, and the operation’s Tier size.

    Site-specific planning and design by a professional that has knowledge and experience with VEBs are critical for VEB effectiveness.

    Since it can take years for VEBs to reach maturity for effectiveness, interim control measures may be needed until VEB reaches an effective growth stage.

Other Producers

Depending on operations at the facility, “Other Producers” with a SRCAA-granted exemption could use a combination of what is listed above for Indoor and Outdoor Producers.