Cannabis growers overcome the powerful scent
Cannabis stinks, its opponents claim, comparing the scent of buds at harvest to skunks.
But beyond its fragrant nose, cannabis enterprise carries an aroma welcome even to many who shun pot: the smell of money.
Cash gushes from the emerging industry. It's expected to soar to billions of dollars a year in California, with Santa Rosa's CannaCom Valley at the heart of North Bay cannabis commerce. But cannabis operators must reckon with the reek, which makes some neighbors smoking mad.
At public hearings on cannabis policy held by Sonoma County's board of supervisors, residents who live near cultivation complained to the board about its pungent smell - especially at harvest. Supervisors responded by banning cultivation in rural-residential zones.
In public comments to Santa Rosa officials about proposed cannabis cultivation sites, neighbors objected to the odor.
SMELL TRAVELS 1,500 YARDS
“I object to the proposed commercial growth of marijuana adjacent to my home,” said Richard Cooper, an attorney who lives near proposed Giffen Avenue cannabis-cultivation sites, all indoors, the largest in Santa Rosa. “My primary objection is against the odor-smell that the plants create. The smell is skunk-like or sewer-like,” Cooper said in his March 17 letter, noting that “the offensive smell travels long distances - 1,500 yards or more. I don't want to have this smell …. Do city officials realize the loss of value my property suffers because of this odor?”
Agricultural commerce brings unwelcome odors. Cow manure annoys folks near dairies. Gilroy reeks of garlic grown nearby. Vineyard managers in Sonoma and Napa counties spray elemental sulfur on wine grapes to ward off powdery mildew. Sulfur can smell like rotting eggs. Cannabis, too, has a distinctive aroma.
Santa Rosa's planning staff sums up how cannabis cultivators at 2835 Duke Court will need to mitigate odor:
“Air within the facility will be ventilated through high-efficiency particulate arrestance filters,” the report said. “Cannabis cultivation and processing rooms include several layers of carbon filtration and fan systems, including scrubbers.”
Duke Court Capital Partners, headed by Steve Monahan of San Rafael, submitted descriptions of carbon-based can filters “designed for the control of VOCs, odors and other gaseous contaminants.”
VOCs are volatile organic compounds such as paint fumes, hydrocarbons.
For industrial engineers, olfactory challenges have a scientific basis in essential oils, according to Jay Takacs, principal at 15000 Inc., a mechanical engineering company in Santa Rosa. Fatty acids occur naturally in cannabis and other plants, and can produce fruity aroma like that of berries, banana or apple cider.
Terpenes - fragrant essential-oil compounds of hydrogen and carbon - in cannabis account for sweet, floral, citrusy or piney scents. The typical smell of cannabis comes from roughly 140 different terpenes, according to “Chemistry and Analysis of Phytocannabinoids,” written in 2007 by Rudolf Brenneisen, professor of phytochemistry at University of Bern, Switzerland. He studied cannabis for 20 years.
Terpenes can have beneficial as well as olfactory effects - antiseptic, anti-inflammatory or antiviral. Myrcene, noted for sedative, analgesic (pain relief) and anti-inflammatory effects, occurs in many cannabis strains as well as in hops, mangoes, thyme, lemongrass and basil. Linalool, a terpene found in cannabis and lavender, is prized for its stress-reduction effects. Pinene in cannabis and coniferous oil such as pine and spruce is strongly antiseptic. Limonene, occurring in citrus fruits as well as cannabis, is powerfully antiviral.
SCIENCE BEHIND THE SKUNK ODOR
Some cannabis critics describe its smell as skunky during flowering. The odoriferous secretion of skunks is primarily volatile thiols: €-2-butene-1 thiol (about 40 percent) and 3-methyl-1-butanethiol (about 22 percent). Cannabis contains alpha-linolenic acid, which may break down under the ultraviolet rays of sunlight into methyl and butyl thiols, according to one scientist's theory.
Whether it's skunky or not, the smell of cannabis becomes a business challenge for which local engineers sniff out solutions.
Extraction involves isolating and concentrating substances in cannabis that have medicinal or psychoactive effects.
Extraction facilities use ethanol and carbon dioxide in processing, which must be managed in ventilation systems. Butane, more volatile, is not allowed in Santa Rosa's CannaCom Valley.
The engineering company also works with cannabis distribution centers.
“Plant matter is broken down,” said Matthew Torre, a mechanical engineer at 15000 Inc. “It is taken out of large bins and repackaged, sent out to dispensaries.”