ranger. >> reporter: the nasal ranger, that is its real name, is a device he has used to quantify how strong an odor really is. >> you're drawing air through these ports that filters out any of the odor. >> reporter: we rode along with filler and his nasal ranger to sniff out a complaint. >> got something. >> reporter: fill early has responded to dozens -- filler has responded to dozens of complaints since 2012. the problem started with legalization of medical marijuana. if the odor registers at a certain point, it can be grounds for a citation. >> i'm not smelling anything. >> can i try it? >> sure. >> reporter: filler says so far he hasn't had to give citations for marijuana. >> two more clicks. >>teeporr: because it typically doesn't exceed the odor threshold on the nasal ranger. >> i don't smell it through here, but i can when i'm just standing here. >> it's a discernible odor. >> reporter: filler can help cannabis cultivators reduce the odor and in denver that seems to be working pretty well. >> here we've got multiple grow facilities. they're right behind you. they're on the oth

this is called the nasal ranger. that is it's real name. a device he uses to quantify how strong an odor, any odor, really is. >> you are drawing air through these ports that filters out any of the odor. >> reporter: we road rode along with him to sniff out a complaint. >> got something. >> reporter: he has responded to dozens of complaints since 2012. the problem started with legalization of medical marijuana. if the odor registers at a certain point on the nasal ranger, it can be grounds for citation. >> i am not smelling anything. >> reporter: can i try it? >> sure. >> reporter: so far, he hasn't had to give any citations for marijuana. it typically doesn't exceed the odor threshold on the nasal ranger. >> it is a discernible odor. >> reporter: he can help cannibis cullty va tors. some are urging for tighter controls. >> we would like to see it regulated here. it needs to be regulated elsewhere as well. >> it looks funny. it is hard to say all of that with a straight face. this is becoming a serious issue. regulation do need some work wh