Old Factories and Olfactory: How the Subjective Sense of Smell Steers Citations

Parts of every city are smelly, occasionally. And in Louisville, several neighborhoods in particular have routinely complained about odors...like some areas of Butchertown near the JBS Swift slaughterhouse, and neighborhoods bordering chemical plants and factories in Rubbertown.

When residents smell odors, they call the Air Pollution Control District, which follows up. But in a Notice of Violation issued to Swift in September, something piqued my curiosity: the compliance officer smelled an odor, while the plant manager did not.

To some extent, smells are subjective. I like the way lilies smell, while my husband can't stand them. And there are a few possible situations to account for the difference in smell perception between the APCD official and Swift employees: the plant manager could have been immune to the smell, because he's used to smelling some variation of it every day, or he was trying to avoid a fine. But it made me wonder: is a good sense of smell necessary to be a compliance officer?

APCD spokesman Tom Nord says yes. Here's how he responded to my question:
While there are devices available that can aid in odor enforcement (such as www.nasalranger.com) a human nose is still needed. We are unaware of any equipment that measures odor without relying on the human sense of smell.  The APCD does not use the Nasal Ranger; we have found that it is not a practical device to use in an urban environment where homes and businesses are located close together and there are a multitude of odors – good and bad – to discern. The APCD is guided by Regulation 1.13, which lays out the rules for odor enforcement. ( http://www.louisvilleky.gov/NR/rdonlyres/FC532232-D4CD-403E-8E5E-83F894BB273B/0/1_13v6.pdf) The regulation defines “objectionable odor” as “any odor present in the ambient air that, by itself or in combination with other odors, gases, or vapors, is offensive, foul, unpleasant, or repulsive.” It also authorizes APCD to use “an instrument, device, or technique” to determine the intensity of an odor.
And Nord says the subjective nature of smells means the APCD relies on several different perspectives.

Whether an odor is objectionable is based on the public's perception as well as a compliance officer's.  For example, we've received complaints about coffee roasters, which some people believe is a good smell.  However, if one is subjected to a strong smell of coffee roasting continuously, it might be considered objectionable. It’s a judgment call, and we give the companies and people we cite a chance to dispute our findings.
That answers my question, but it does make me wonder: what does a compliance officer do if they're crippled by allergies--as so many people in the city are--and temporarily lose their sense of smell?