One day about lunchtime, a patron walks up to the desk and said:
I just stopped in on my lunch hour to pick up some things I had on hold, but while I was here I thought I'd ask: is there a measurement for smell? Someone in my office uses our microwave to cook his lunch and usually it smells bad. Is there a way to measure how bad it smells, so we can tell him he can't cook things that smell worse than X?
Let me tell you right now, I love this question.
And honestly, I had no idea. I know sound is measured in decibels and light is measured in candlepower or lumens, but I've never heard of a measurement for smells (or for taste, for that matter. Touch I suppose is PSI).
My favorite go-to source for questions like this (definitions in search of a word) is the Descriptionary, but it turns out our copy is missing. So, being pressed for time with the patron on his lunch break, I just searched the internet for unit of measurement for smell, which brought us to the Wikipedia article for Odor, which has a "Measurement" section.
Our quick skim indicated two aspects involved in measurement - concentration and intensity - and that it appears there is no easy way to measure smells (nothing like a convenient light meter, for example). Measurement seems to be done in labs by professionals, using carefully controlled sample. We did learn, however, that there is a 0-6 scale for smell intensity, and that the unit of measurement for smell concentration is the European Odor Unit, (OUE).
We were both kind of disappointed at this point - I think we were hoping for a little handheld device that you could stick in a room and it would give a quantitative reading like "42 stinks" or something. The patron had to go, so I took his name and email address, and told him I'd send him anything else I found.
And I did find more, but nothing that would really help. Here are some of the highlights:
- Devices that measures smells are an olfactometer and an electronic nose
- Glossary of scent and smell terminology
- From a different glossary:
- Olf: an empirical unit of indoor odor intensity introduced by the Danish environmental scientist P.O. Fanger in 1988. One olf is defined as the odor intensity produced by one 'standard' person (a standard person is also defined). The name comes from the Latin olfacere, to smell. Ventilation reduces pollution, and the resulting pollution in ventilated, enclosed spaces is measured in decipols.
- Decipol: an empirical unit of indoor odor intensity introduced by the Danish environmental scientist P.O. Fanger in 1988. One olf is defined as the indoor odor intensity produced by one "standard person", and one decipol is the perceived odor intensity level in a space having an odor source of strength one olf and ventilation at the rate of 10 liters/second with unpolluted air. Measurements are recorded by human observers using protocols laid out by Fanger and his colleagues.
- Popular Science article on two Cornell students who created a machine to quantify farts
- Further reading:
- Discover Magazine article on how the brain processes smells
- What is an odor unit
- Is odor measurement subjective or based on science
That was the academic information I found. For non-academic information, I also found:
- Hobo Power: Coined by Adam Carolla and Dr. Drew on the radio show Loveline as a measure of how bad something smells. Ranging from 0-100, anything near 100 hobo would smell bad enough to cause death by asphyxiation.
Although more colloquial than OUE, I don't like this, because ever since I was little I wanted to be a hobo. But not everyone must share my romanticized view. A quick breakdown of the Hobo Power scale can be found here, and it's also listed in the Urban Dictionary.
I liked the "Olf" the best, but without any way to really measure it in the field, it's still not very helpful to the patron. I sent him what I found, with a note that I'll keep looking, but unfortunately I don't have much hope for finding something that will prevent his office lunchtime odors.