Space & Innovation

Why Can't We Smell Things When It's Cold?

Do things smell worse in the winter... or summer? How and why does temperature affect our sense of smell?

Stalwart reader Sydney Flowers recently wrote to ask "How does temperature affect your sense of smell?" We're not sure what dilemma or scheme prompted this question, Sydney, but here at DNews we live to serve -- so we looked into it.

First, some evolutionary context: The human nose evolved to reveal information about our environment that we can't otherwise apprehend via sight, sound or touch. When you smell something, physical particles in the air are entering your nose and hitting specialized olfactory receptors. This is a disquieting notion, to be sure. When you smell that guy on the bus, you're literally inhaling microscopic bits of said guy. Tragic but true.

These particles or odorants are what's known as "volatile." That's the scientific term for any substance or material that gets into the air itself at regular temperatures, and it's at the root of the question, really. Temperature does indeed affect volatility. For instance, a 2003 study in the journal Drying Technology -- there's a journal for everything -- found that pine trees release more odorous volatiles as they get hotter and dryer.

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Another study, in yet another oddly specific journal, tracked the smell of salami at various temperatures. You will be pleased to know that salami smell is at its most intense at 122 degrees Fahrenheit.

Further research over the years has delivered details relevant to the question. Humid air is generally better at trapping and delivering odorants through the atmosphere, and better at depositing those particles to the associated olfactory receptors. Winter air is drier and therefore delivers odors less efficiently. In addition, colder temperatures inhibit the initial release of volatiles coming off pine trees, salami, guys on buses, what-have-you.

So ... while it's true that you're less likely to encounter strong smells in colder temperatures, it actually has nothing to do with your nose. (Unless your nose is plugged up.) Rather, you smell less because there are less smells. Rather Zen, isn't it?

Thanks for writing in, Sydney. If you've got a question for our crack team of weird science investigators, drop a line via Twitter, YouTube or Seeker.com.

-- Glenn McDonald

Learn More:

Physiology Online: How We Smell: The Molecular And Cellular Bases Of Olfaction

Oxford Journals: An Environmental Nuisance: Odor Concentrated And Transported By Dust

NBC News: Ooooh, That Smell! Odors Rise With The Temperature