Recreational marijuana is legal in Colorado. But that doesn't mean residents want the air to smell like a pot rally...And that's where licensed smell investigator Ben Siller comes in. A member of Denver's Department of Environmental Health, he's trained to use an olfactometer to determine if people are breaking laws that protect the purity of Denver's air.
— Read more at Denver's Smell-O-Scope Targets Marijuana's Skunky Scent at NPR. Plus, read more about the Nasal Ranger Field Olfactometer here.