Denver environmental health investigators use Nasal Ranger gadget to crackdown on pungent pot odors

Complaints are often about pot-growing smells

DENVER - Marijuana has gone from being illegal, to medically legal, to just about completely legal in Colorado.

Now, the City and County of Denver says it is dealing with an increasing number of marijuana odor complaints.

The complaints are primarily about the powerful odor generated by businesses growing marijuana plants -- not people smoking pot, said Ben Siller, an investigator for the Denver Department of Environmental Health.

Data obtained by 7NEWS shows that between 2010 and 2012, the number of marijuana odor complaints more than doubled. Seven were filed in 2010 and the Department of Environmental Health investigated a total of 16 in 2012.

"Initially, we received complaints just because (marijuana businesses) were starting up and some of those complaints were just because of the unknown that there was this new business in the area with odor coming from the facility," said Siller.

 So far this year, the total number of pot-related odor complaints is down in Denver, but marijuana accounts for one out of every eight odor complaints.

 Siller is responsible for investigating these complaints.

 "For the odor check, we will use this Nasal Ranger," Siller explained.

The Nasal Ranger device is owned by the department and helps investigators detect the intensity of an odor by filtering out the odorous air.

 "We have spoken to the marijuana grow operators. We let them know that there is a complaint and we have asked them to be proactive to try and mitigate the odors coming out of their facilities," Siller said.

If the odor reaches a level of 8:1 or greater, that's a violation of Denver's odor ordinance. A violation can result in a fine of up to $2,000.

7NEWS traveled with Siller to an unidentified marijuana grow operation in Denver where a complaint had been filed. The odor at the location wasn't strong enough to warrant a citation.

"We went through the Nasal Ranger and all the ports and nothing was picked up at even 2:1," said Siller.

"We also have a provision in our ordinance that if we receive five complaints from households in a 12-hour period for a specific source, then that would constitute a violation as well," said Siller.

7News has learned that even when the smell isn't overpowering, the city has come up with new ways to try to manage these types of odors.

"We did establish what we call a best management practice guide that gives marijuana operators information about all the different sorts of environmental issues that we might encounter from odors or air quality to water quality discharges," said Gary Lasswell, Denver's Manager of Environmental Operations.

Lasswell tells 7NEWS the department is already preparing for another spike in complaints when retail marijuana is sold legally for the first time on Jan. 1, 2014.

"We are going to be increasing our staff level, adding a person that would be devoted strictly to dealing with marijuana," continued Lasswell.

He says he doesn't see an immediate need for stricter marijuana odor regulations yet.

For now, 2014 will be wait-and-see -- or more appropriately, wait-and-smell.

"There is not a requirement that they have to have ventilation, but we certainly recognize the controversy surrounding marijuana and the regulation of marijuana," Lasswell said of marijuana businesses.

To find more information about how to make an odor complaint, visit:

You can also read about "Best Management Practices: Commercial Medical Marijuana Cultivation" at

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