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 6.18 – Standards for Marijuana Production and Marijuana Processing, in January 2018. Requirements are summarized below.

Annual Registration

Prior to operating, marijuana producers and processors in Spokane County must register with Spokane Clean Air. After initial registration, we will send annual registration packets in March-April of each year. The packet includes a form to complete and submit, and an invoice for the annual fee to pay. Per the regulation, registered facilities are required to pay the entire annual registration fee even if the facility only operated for a portion of the year.

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

Requirements that apply to all operations

  • Notification of any changes – all facilities, regardless of type, must notify us of any changes in operations. This also includes business closure, change of ownership, and name change. Additionally, before considering an expansion and/or relocation, contact us to determine what requirements apply to your type of facility.
  • 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, regardless of type, must meet the odor rule: Article VI, Section 6.04.

Requirements by type of operation

Producers propagate, grow, harvest, and trims marijuana to be processed. There are three distinct 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. All processing must occur indoors.

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. 

Indoor Producers are required to:

  • Use air pollution control equipment, facility design, or both to reduce air contaminants.
  • Keep doors and windows closed, except for active ingress and egress. 
  • Follow an Operations & Maintenance plan for air pollution control equipment
  • Keep maintenance records.

Outdoor Producer

Outdoor Producers are operations on an expanse of open or cleared ground (no structures of any kind) and 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.  

Outdoor producers are required to:

  • 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(s).

Other Producer

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

Other Producers in operation when the regulation became effective were provided a one-time written exemption if they applied for such exemption by November 5, 2018. Those granted exemptions must comply with specific conditions of their production exemption. New or expansion of existing operations are not allowed.


Processors are operations that dry, cure, extract compounds, convert, package, and/or label usable marijuana and marijuana concentrates. All processing must occur indoors.

Processors are required to:

  • Use air pollution control equipment, facility design, or both. 
  • Keep doors and windows closed except for active ingress or egress. 
  • Follow an Operations & Maintenance plan for air pollution control equipment and keep maintenance records.

A processing exemption is available for processors that only purchase marijuana concentrate (e.g. oil) to manufacture infused products. There is no fee to apply and those granted an exemption are not required to register or comply with Article VI, Section 6.18, but must still meet SRCAA’s odor regulation.

Potential Odor, Emissions Control Measures for Indoor Operations

The following controls and practices have been employed alone or in combination at some marijuana production and processing operations. It is imperative that Control equipment be properly-sized for the amount of airflow being treated. In addition, 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 – A 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.

Potential Odor, Emissions Control Measures for 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.

Potential Odor, Emissions Control Measures for Other Producers

Depending on operations at the facility, “Other producers” with an Agency-granted production exemption, could use a combination of what is listed in Indoor and Outdoor.