The Nuts and Bolts of Cannabis Odor Control

March 15, 2025

A standing-room-only crowd packed into Carpinteria City Hall on Friday, eager to advise three Santa Barbara County supervisors on how best to get rid of the smell of pot that drifts around town from the cannabis greenhouse industry.

The community forum was convoked by Laura Capps, chair of the county Board of Supervisors, and Supervisors Roy Lee and Bob Nelson. None of them were on the board in February 2018, when the county’s unpopular cannabis ordinance was approved. They reminded the crowd that next Tuesday, at their initiative, the board will amend its cannabis regulations to control the smell of pot in the Carpinteria Valley.

Specifically, Capps said, the board will give cannabis growers in the valley 12 months to install state-of-the art carbon filtration systems known as scrubbers — or an equivalent technology. Scrubbers have been proven to clean up the pungent odor of pot inside a greenhouse before it can escape through the roof vents.

At the same time, the growers would be required to shut down the “misting” systems that they are currently using to neutralize the smell of pot, after it escapes into the outside air.

These major changes are in the works, Capps said. The goal of the Friday’s forum, she said, was to hear residents’ views on three additional questions: How to set a threshold for cannabis odor at the greenhouse property lines; what technology to use to test the odor there, and whether to allow extensions to the 12-month deadline for installing scrubbers.

“I believe this is historic, for the supervisors to come to you,” Capps said. “ … The goal of this is to convey that the county is connected to the City of Carpinteria and the people of Carpinteria, greatly so.”

Since 2018, Carpinterians have filed more than 3,900 odor complaints to the county regarding the “skunky” smell of pot and the “laundromat” smell of the misting systems. But the county did not enforce the complaints because it was impossible to determine which “grow” was responsible. During those years, the Carpinteria City Council sent 24 letters to the county, pleading for stronger regulations to rein in the burgeoning cannabis industry just outside city limits.

Then, last year, Roy Lee, a former Carpinteria councilmember, was elected to the county Board of Supervisors, largely because of the 2-1 margin in his favor in Carpinteria. Lee took office on Jan. 1, replacing Das Williams, a fellow Carpinterian who had been a co-author of the cannabis ordinance.

“If you had told me a few years ago the Board of Supervisors would be here, I wouldn’t have believed you,” Lee told the crowd on Friday.

Other county officials at the forum included County Executive Officer Mona Miyasato, Deputy County Executive Officer Brittany Odermann, and employees from Planning & Development and the County Counsel’s office.

“This Board of Supervisors has had a seismic shift in attitude,” Paul Foley, an avocado grower, told the gathering. “The people, to some degree, have spoken.”

Residents crowded into a Carpinteria City Hall forum on Friday to advise three county supervisors on how best to tackle the smell of pot from the local cannabis greenhouse industry. | Credit: Carl Perry.

‘We Try Our Best‘

To date, the county has approved zoning permits for 27 cannabis greenhouse operations in the valley, covering 138 acres just outside the city limits of Carpinteria. Nineteen of these operations are actively cultivating cannabis on roughly 120 acres, or about 90 football fields’ worth. Of the active “grows,” only seven are equipped with scrubbers.

The growers in attendance at Friday’s forum defended their efforts to control the smell of cannabis. They noted that Ever-Bloom, at 4701 Foothill Road, and the Glass House Brands operation at 5601 Casitas Pass Road, have both installed state-of-the-art scrubbers from the Netherlands. These have been proven, on average, to eliminate 84 percent of the smell of cannabis inside a greenhouse operation. But at $22,000 each and a recommended density of eight to 12 per acre, these scrubbers are expensive.

In addition, it has taken six months at some operations to complete the necessary power upgrades to accommodate the new technology, the growers said.

“We welcome the scrubbers; we’re not opposed,” said Tiffany Garcia, the head grower in the valley for Glass House, a vertically integrated company based in Long Beach, Calif. “ …The cost associated with all these odor systems is through the roof.… We do try our best to do right by our community.”

After a speaker told the supervisors that the misting systems left an oily residue on his patio furniture, Graham Farrar, the Glass House president and co-founder, reminded residents that the growers had installed the systems because the community demanded them. He said it was costing him $1,000 per day to operate his misting systems.

“I’m happy to see those and their associated costs go away,” Farrar said.

Other speakers noted that cannabis growers, unlike the avocado growers in the valley, are not spraying pesticides on their crop. They reminded the crowd, too, that the cannabis industry has provided jobs for Carpinteria’s large Latino community.

“I don’t mind the smell,” Ben Wilmore said. “We’re right by a farm as well. It doesn’t bother me. What I think about when I smell cannabis is the reduction of harmful pesticides in our community.”

Referring to the growers, Wilmore said, “I would just hope that you don’t vote on something that puts them out of business. Because we need them here. We love having them here.”

Capps responded that there was a consensus among the supervisors that “we’re not interested in putting people out of business.”

Zero Odor?

Under a county Planning Commission recommendation to the board, the odor threshold for compliance at the greenhouse property lines would be set just below the “nuisance” level, defined as the level at which the smell is “noticeable” but not “faint.”

The City of Carpinteria favors setting the odor threshold a bit lower, at “faint.” But on Friday, a number of residents, including members of two citizens’ groups — Concerned Carpinterians and the Santa Barbara Coalition for Responsible Cannabis — spoke in favor of a “zero odor” threshold at the greenhouse property lines.

“It should not be leaving the building,” Gail Herson said.

CARP Growers, an industry trade group, wants the county to set the odor threshold above “noticeable” at the property line. Anything lower would be impossible to detect and would amount to punishment of the industry, growers told the supervisors on Friday.

“If the odor threshold is zero, then the ocean is illegal, cutting your lawn is illegal, making bread is illegal, roses are illegal,” Farrar said. “An odor threshold of zero does not actually exist. The question is, where does something become intrusive to other people’s rights?”

(Farrar has installed scrubbers at his Glass House operation at 5601 Casitas Pass Road, but not at at G&K at 3561 Foothill Road, a frequent target of residents’ odor complaints.)

At the mike, Graham Farrar of Glass House Brands said it would be impossible to implement a “zero odor” threshold at the property lines of cannabis greenhouses. | Credit: Carl Perry

William Cole told the supervisors that he lives a couple of miles away from any cannabis greenhouses, but, he said, the smell “hops locations,” “floats like a cloud of natural gas” and settles at the bottom of his house. He suggested setting the odor threshold at the “noticeable” level and then observing how the widespread use of scrubbers was working to eliminate the smell. If necessary, the threshold could be tightened, Cole said.

Jamie Collins, the executive director of Girls Inc. of Carpinteria, urged the supervisors not to implement odor thresholds at this time.

“It could put our growers out of business,” she said. “People work in these farms and need jobs, and we can’t lose them.”

Odor Drift

The county is proposing to send inspectors out with portable Nasal Rangers to sniff the air at the greenhouse property lines when residents file complaints. But Nick Bobroff, the City of Carpinteria’s community development director, urged the supervisors instead to look into how other “noxious industries,” such as municipal dumps, wastewater treatment plants, and compost facilities, measure the odor at their property lines.

Mike Wondolowski of the Carpinteria Valley Association noted that the smell of pot can skip over the property lines of greenhouses and may not be detectable there. Typically, he said, it rises with warm air vented from the greenhouses during the day, then pools and comes back down in the cool of the night.

“On summer evenings in Carpinteria, the odor moves like a slow wave down toward the ocean,” Wondolowski said. “It’s predictable. At my house, it’s about 20 minutes after sunset.… That means that detection on the fence line might be zero when there’s odor that’s already gone up, over and down somewhere else.”

Wondolowski said the supervisors should consider implementing “proactive enforcement” through the use of gas chromatography to measure the odor of cannabis at the greenhouse roof vents. Gas chromatography measures the chemical components in air samples and can identify the “markers” of cannabis odor.

Mike Palmer of Ever-Bloom then took the mike to say that he has found that gas chromatography can result in “false positives” and “false negatives.”

As the forum wound to an end, several speakers asked the supervisors not to extend the 12-month deadline for the installation of scrubbers. John Culbertson said the county should think of the problem as an “air pollution issue” rather than an “odor issue.”

“Let’s not get complacent,” he said. “People have really been hurt by this failure of county governance. We are so thankful for the three supervisors who sit in front of us. Stay on task.”

In his closing remarks, Supervisor Lee said he did not favor extending the 12-month deadline for scrubbers in all cannabis greenhouses. On Tuesday, he said, the board will likely require all valley growers to sign a sworn affidavit agreeing to install them. If they fail to make the installation, their business licenses will likely be revoked, and they could be subject to felony prosecution, Lee said.

“It’s happening,” he told the crowd. “I long suffered with all of you through this. Change is coming.”

Melinda Burns is an investigative journalist with 40 years of experience covering immigration, water, science, and the environment. As a community service, she offers her reports to multiple publications in Santa Barbara County, at the same time, for free.