The Nasal Ranger, according to its product website, is a field olfactometer, which is a portable odor detecting and measuring device, a nasal organoleptic instrument, an instrument for measuring ambient odor dilution-to-threshhold, and a “scentometer.”  NBC News reports that the Nasal Ranger looks like a narrow bullhorn and is sometimes called a “nose telescope” because it is able to identify odors.  The Nasal Ranger works by pressing the narrow end up to the user’s nose.

The interior is coated with Teflon to resist residual odor buildup. When the user inhales, air enters the device through carbon filters at increasing degrees when a dial is turned up at the wide end.  When the user detects a stench, the numerical reading on the dial is noted. For example, in Denver, a violation occurs when the offending odor is at a 7:1 ratio or, in other words, when one unit of odor is detectable per every seven units of air in the Nasal Ranger.

The Nasal Ranger has been used to investigate odor complaints against landfills, manufacturing plants and oil refineries. Users must first pass an odor sensitivity test.  The test uses “sniffin’ sticks,” which are small pens that contain different concentrations of odors.  In order to use the Nasal Ranger, the prospective user must already have a sufficiently sensitive nose. The Nasal Ranger is considered a possible tool for odor evaluations as more jurisdictions legalize pot.  With legalization, users are unlikely to try to cover up the smell.

The Denver Post describes use in the capital city of Colorado, a state that recently legalized recreational marijuana use.  In the dawning age of legal marijuana in Denver, the city is getting more and more complaints about the unmistakable odor wafting through the streets — a skunky, herbal scent that has prompted dozens of calls to the city’s hotline.  However, odor alone is insufficient to break the odor law, which is determined by the volume of the smell.

According to a History Channel episode of Modern Marvels, the Nasal Ranger is able to quantify an odor by detecting the volume of odor in the air.  This is useful for enforcement of odor laws, managing odors in agricultural settings, and evaluating the odor of products before their release.  However, marijuana use rarely reaches an odor level that actually violates the law.  In fact, it has not happened since 1994. Odors would have to be pretty strong, an industrial-level aroma, like what would come from an ill-managed rendering plant.