The Nasal Ranger Field Olfactometer is a gadget for empirically measuring the presence of stink-particles in a given environment. It is being deployed in Denver to measure compliance with a by-law prompted by Colorado's rules for legal marijuana: you're allowed to smoke weed, but you are not permitted to spread the smell of marijuana into your neighbors' spaces.
In order to combat this kind of pot pollution, the city of Denver has passed a new "odor ordinance" that carries a $2,000 fine for anyone found guilty of polluting the atmosphere with smell. So, to investigate odor complaints more effectively, Denver Police are using a ridiculous bit of tech called the Nasal Ranger Field Olfactometer – a device that's basically a handheld smelloscope.
It's actually a pretty ingenious device. It works by delivering varying ratios of filtered and full-odor air to the operator's nose. Mellow smells tend to wash out when mixed with small quantities of purified air, but a particularly odiferous smells can remain detectable at a 500:1 ratio. Check out this video from the History Channel's Modern Marvels to get a better idea:
Denver cops use "smell-oscopes" to sniff out dope smokers [Drew Prindle/Digital Trends]
(via Oh Gizmo)