https://www.vice.com/en_us/article/y3mnak/how-a-city-decides-to-buy-this-ridiculous-dollar2000-weed-smelling-device

For a few thousand dollars, cities are purchasing a device that bears striking resemblance to the Smell-O-Scope from the TV series Futurama to sniff out weed and fine smokers and growers if the scent produced is too strong.

The Nasal Ranger, a field olfactometer advertised as allowing users to conduct “complete odor monitoring, regulation, enforcement and documentation,” has been employed by officials in Denver and Las Vegas. Correspondence obtained by Motherboard via a freedom of information request between officials in one Michigan city and St. Croix Sensory, the company that manufactures the Nasal Ranger, shows that cities are interested in the device for one smell in particular: weed.