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A discerning nose: "Odor Ranger" monitors marijuana smell

In an effort to monitor smell at a marijuana greenhouse near Basalt, Pitkin County has hired an “odor ranger.” He’s been tracking pot aroma for more than a month. It’s an attempt at taming one aspect of a new industry. But, few rules exist in Colorado around smell and marijuana. Aspen Public Radio’s Marci Krivonen has more.

It’s mid-day along Highway 82. Ryan Randolph looks both ways and runs across the busy road. He’s in front of High Valley Farms.

"So once I get to this point, this is where the test starts."

Randolph was hired by Pitkin County to monitor the air here. He visits this stretch of highway twice a week, unannounced.

"We walk to the end of the property line that way and then we turn around and walk to the other end of the property line, that way. And then we come back to this point. That way, the entire property line gets two passes."

It’s a simple test that uses one primary tool — his nose.

"Sometimes I can smell aspen trees, flowers, or a car with a smell wafting from it. But I can tell the difference between smoke and the fresh smell," he says.

Credit Marci Krivonen
Randolph keeps a running record of whether he smells pot. He's drawn up a standard operating procedure for gauging whether it's coming from High Valley Farms.

He’s developed a standard operating procedure. In order to get a positive detection, the smell has to be distinct and persist for 15 seconds. Since he began in mid-September, he’s logged no positive detections.

"What we found with odors in general, and marijuana odors, is that it is a discernable odor. It’s there, but it’s faint," says Ben Siller.

He's with the City and County of Denver’s Department of Environmental Health. He’s monitored smell at dozens of marijuana grow operations.

"We stand off-property, downwind and we use this device called the Nasal Ranger. I like it because it takes the subjectivity out of it. It’s not about the quality of the odor, it’s simply about the intensity or strength of the odor.”

If the Nasal Ranger spits out a reading that exceeds Denver’s odor threshold, the grow operation may get fined. Out of 300-plus grow operations, however, none have violated the city rule.

With state law, it’s hard to offend. Marijuana operations are classified “agricultural,” so they’re exempt from most rules. Christopher Dann is with the state’s air pollution control division. He says one rule can be broken.

"The regulation is not based on whether something smells good, bad or otherwise. It is simply the intensity and for the most part a pretty high threshold. It’s not violated on a regular basis."

In fact, no marijuana operations have violated the state rule.

Neighbor complaints are what led to the air monitoring program at High Valley Farms near Basalt. It was a stipulation for the grow operation to continue. Kurt Dahl is the county’s Environmental Health Manager.

"That was one of the pieces that was discussed (at a commissioner's meeting in Sept.) that we were going to have third party monitoring at that the county was going to assume responsibility for doing that."

Randolph is employed by the county but High Valley Farms pays his wages. He’s paid more than $100 an hour. The business also installed carbon filters to kill the smell. Again, Dahl.

Dahl: "The overall goal is to not have a negative impact on that area from any odor that might be coming from High Valley Farms."

Reporter: “Since this monitoring program has started, have you had any complaints from neighbors?”

Dahl: “I’ve had one neighbor who complained about odor and I think that is something that we’re still looking into.”

Back along Highway 82 Ryan Randolph is almost done with today’s test.

Randolph: "I don’t like this part when my back’s to the traffic.”

Reporter: “Yeah, we’re really close to the traffic.”

Despite the risks, Randolph says he’s happy to do this work. The chemist-by-trade says he likes being part of a pioneering industry.

"It’s different. It’s not something I expected to do when I quit my job in pharmaceuticals and moved out to Colorado. But it came up and I think it’s a great opportunity for me and for the industry to start thinking about a model for odor mitigation."