Grow operations often put plants on mobile racks, such as these shown here. - Spacesaver

Grow operations often put plants on mobile racks, such as these shown here.


Over 43,000 people call California’s Canoga Park home. But the area is also home to a smattering of marijuana dispensaries, grow operations and retail stores.

This is not newsworthy by itself. California became the first state to legalize marijuana in 2012. What is noteworthy is the fire potential these cannabis facilities present.

In October, three people suffered injuries after several explosions in a Canoga Park marijuana grow facility. Flames tore through the building, sending smoke billowing across the area. It took 150 firefighters over an hour to get the blaze under control, but not before it destroyed the single-story building and damaged two neighboring structures.

This scene plays out all too often whenever U.S. cannabis facilities catch fire, says Brian Lukus, P.E., Fire Protection Engineer at the Denver Fire Department and member of the Society of Fire Protection Engineers (SFPE). In his role, Lukus focuses on regulating fire protection at cannabis facilities.

He explains no fire codes specific to cannabis operations existed when states began regulating marijuana a decade ago. Since then, codes have slowly crept into the industry. “They cover things like when you grow plants indoors, how do you protect them? Or sprinkler placement. But the codes often relate to agricultural buildings [and are not specific to the industry itself],” he says.

The City of Denver has taken steps to improve fire protection at these facilities in the absence of specific codes. The Denver Fire Department targets things like CO2 enrichment and the dangers it poses, extraction processes and flammable liquids, rack storage and the danger of collapsing racks, fertilizer use, and more. But more awareness and fire codes are needed, Lukus reports.

Know the Type of Facility

Knowing the type of facility and the hazards it presents is the first step to better fire protection, stresses Lukus.

Most marijuana facilities focus on a specific aspect of the industry: growing, processing or selling, and each presents unique hazards and safety issues. For example, grow operations pack plants in warehouse buildings and processing operations use chemicals to extract oils from plants.

Look for CO2 Hazards

Grow operations present unique safety considerations, adds Lukus. Growers locate these operations in large warehouses that they subdivide into smaller rooms. They closely monitor rooms for optimal growing conditions and move plants throughout the building as they reach various developmental stages. The rooms holding plants often contain hot lamps, electrical wires and water, all of which can lead to a fire.

The plants themselves do not present a fire hazard. Grow operations keep soil moist and plants damp. However, the CO2 enrichment process used to increase yields presents concerns.

“Operators fill grow warehouses with carbon dioxide to encourage plants to grow faster,” Lukus explains. “These facilities hold compressed CO2 gas systems and natural gas burners, which can put CO2 and carbon monoxide into the environment. Those are two hazards you have to protect against.”

The off gassing of CO2 in the air during the enrichment process can produce headaches and drowsiness at low levels, impaired breathing, increased cardiac output, elevated blood pressure and increased arrythmia at high levels. Prolonged exposure can lead to death by suffocation.

Knowing this, Denver regulates CO2 levels in these facilities, drawing from code requirements for the beverage industry, Lukus says.

“There have been deaths across the country from leaking fittings and below-level areas where CO2 gets trapped,” he says. “We require a home run from the supply tanks to the enriched room, using piping without fittings between the two. We also require fail-safe CO2 detection systems in the room and at supply locations.” Further, whenever the system alarms at 5,000 parts per million, the operation must stop the flow of CO2.

What does CO2 enrichment mean for firefighters? It means they should always respond wearing SCBA and use a handheld CO2 detector to monitor levels in the air. “First responders need to realize that even if they’re just responding to a patient-down call, they could walk into a CO2 enriched environment,” he says.

Sprinkler Considerations

Grow facilities packed with plants can become a maze for first responders to navigate and an obstacle for sprinklers, adds Lukus.

He stresses codes and standards also fall short here. The NFPA bases NFPA 13, the current standard for sprinkler system installation, on plants up to 12 feet tall. But Lukus reports many facilities grow plants far taller.

“Our highest one in Denver is growing at approximately 30 feet on racks,” he says. “NFPA 13 does not address those situations. We’ve also seen mobile collapsing racks like what you’d see in a doctor’s office. NFPA 13 also does not address how to protect mobile racks holding plants.”

Lukus says engineers must consider these things in facility design. They must know how tall plants will get, and the lighting and rack systems used, then submit a sprinkler system design. “None of this is very well defined in the storage chapters of NFPA 13,” he says. “The mobile racks represent an entirely new code world to address. The industry is moving toward mobile racks because they can install lighting and watering systems on them and increase the area for plants.”

Denver regulates mobile racks as high-pile storage and follows standards in place for those systems. “Once they get over 12 feet, It’s considered high-pile storage. This impacts the protection scheme, the fire access doors and the sprinkler systems,” he says.

Fumigation and Fertilizer Concerns

Grow rooms also rely on fumigation and fertilizer to keep plants healthy, adds Lukus.

Operators fumigate plants with sulfur dioxide to prevent powdery mildew from accumulating on them.

“Sulfur dioxide can be corrosive when present with water vapor, which really wreaks havoc on the CO2 detection equipment,” Lukus says. “This creates concerns over impacts to neighbors and occupants in the building.”

Pesticides also present a problem, he says. Growers apply pesticides to plants to eliminate pests and encourage plant growth.

Operators must address both situations through proper ventilation. “We also require operations to post warnings to those who may enter grow rooms after a pesticide application,” he says.

The extraction process removes chemicals from plants for cannabis products using solvents, such as LP gas or carbon dioxide. - THC Safety

The extraction process removes chemicals from plants for cannabis products using solvents, such as LP gas or carbon dioxide.

THC Safety

Processing Facilities

Processing facilities transform marijuana plants into products for consumption. Here, it’s important to pay attention to the extraction process, which removes chemicals from plants for cannabis products using a solvent, such as LP gas or carbon dioxide.

The systems used for extraction present fire hazards, Lukus says. Though manufacturers describe them as “closed-loop systems,” he stresses they are “anything but. They are opened every time workers retrieve the oil extracted from plants.”

Off gassing also occurs when workers remove plant material soaked with LP gas. The third hazard is potential system failure if the system leaks or ruptures, he adds.

Departments must identify the hazardous materials used in extraction and know where and how much hazardous material sits in controlled areas. When designing processing facilities, engineers also should install a hazardous exhaust system to scrub the air of hazardous gasses.

“We also require protecting these rooms with fire suppression and gas detection systems,” he says. “The detection systems must alert operators of hazardous gasses in the air because they can’t see or smell the gas when there’s a leak.”

Inspections and Preplanning

Denver inspects cannabis facilities twice a year, which Lukus says is critical to fire prevention. “Operators often modify their operation and the building's construction,” he says. “Inspections examine if they are following the original plan for the facility and its processes.”

Lukus says most often inspectors find operators have changed their extraction equipment, use unapproved supply tanks, add different filters, or connect differing manufacturers’ equipment without approval or permits.

“We often see spray foam put in without a building permit,” he says. “But exposed spray foam in a building is a very large fire hazard. Building codes require it to be covered with a 15-minute thermal barrier.”

Beyond inspections, he says preplanning aids fire response. Denver requires operators to post a graphic map at the main entrance of grow facilities and for firefighters to visit facilities and preplan fire response. “These buildings are really chopped up with corridors and smaller rooms,” he says. “It’s like a maze and without preplanning, a firefighter could enter and potentially get lost.”

He adds preplanning also looks at doors and the methods used to secure the facility. “Is it easier to go through a wall than to force the door open?” he asks. “That should be part of the preplan. In Denver we also require operators to install locked key boxes for firefighters to gain access.”

Preplanning response to extraction locations also requires firefighters to identify the hazardous materials used and stored on site, in what quantities, and where.

Future Standards

The NFPA has started developing NFPA 420, Standard on Fire Protection of Cannabis Growing and Processing Facilities. The new standard, which was proposed in response to serious fires at cannabis facilities in recent years, will provide clear guidance on fire protection standards for facilities that produce, process and extract cannabis. 

The NFPA reports the new standard will build upon NFPA 1, Fire Code, which addresses fire protection at growing and processing facilities. The new stand-alone document will address fire protection and other hazards in more detail in facilities where cannabis is grown, processed, extracted and/or tested. 

“With the rapid legalization of medical and/or recreational use of cannabis throughout the U.S. and the exponential growth of cannabis facilities around the globe, developing provisions that minimize fire and associated risks for facility staff and first responders—as well as nearby structures and occupants—is critical to safety,” said Kristin Bigda, technical lead of building and life safety at NFPA, in a press release.

In the meantime, the best defense is a good offense. The more that departments understand about how these facilities operate, the safer the facilities, their employees and first responders will be.