New Study Helps Explain Why Your Hiking Clothes Smell So Bad
We all know hikers don’t smell awesome, but have you ever wondered exactly why our natural fumes are so heinous? Fear not, for there is a valid scientific explanation for your hiking shirt smelling like a sewer rat died inside a bag of old Fritos.
A new study by researchers from Canada’s University of Alberta and New Zealand’s University of Otago sheds light on why some types of fabric absorb odors more than others. The researchers exposed six types of textiles to a synthetic sweat solution and measured how many odorous volatile organic compounds came out of the fabric between 30 minutes and 24 hours from exposure.
Which Fabric Smells Worst, and Why?

Rebecca Sperry photo
The results are … well, pretty obvious to anyone who has worn the same unwashed, sweaty hiking clothes for days on end. In a nutshell, polyester was the worst-smelling fabric in the long run, cotton was the best, and wool and nylon were somewhere in the middle (smelling really bad at first but dissipating the odors relatively quickly).
The researchers offered a fascinating explanation for this dynamic. Turns out the same properties that make your hiking clothes stink are also the properties that make them great hiking clothes.
It’s all about moisture management, you see. Sweat is mostly water, but it also contains oily compounds that are a food source for odor-causing bacteria, as study lead Rachel McQueen explained to Folio, the University of Alberta’s brand journalism site. It is the metabolic processes of those bacteria that make you (and your clothes) smell.
Which fabric smells the worst is largely a function of whether it absorbs more of the water from sweat or more odorants and oils. Cotton absorbs mostly water (and a lot of it), soaking up less of the oil that causes bacteria to flourish.
Which Fabric Makes the Best Hiking Clothes?
But as we all know, the fact that cotton absorbs tons of water makes it a poor choice for outdoor clothing. Some outdoor experts say “cotton kills” in the backcountry because it soaks up so much water and is slow to dry, putting hikers at risk of hypothermia.
Polyester, in contrast, doesn’t absorb much water but soaks up relatively more odorants and oils from sweat. That means it will dry more quickly and be less risky for hikers, but it also creates an ideal environment for odor-causing bacteria.
The researchers looked at how much odor textiles released 30 minutes after absorbing sweat as well as how they smelled over the next 24 hours.
Like polyester, nylon and wool released a lot of funk initially, but they also dissipated those odors more quickly, suggesting they should smell relatively fresh the following day even without laundering. Great news for the merino wool industry: that oft-touted claim that wool is a more odor-resistant outdoor textile appears to be supported by empirical research.
Wool and nylon may therefore be the better choice for outdoor clothing. They still manage moisture and dry quickly like polyester, but they also won’t smell as bad when you pull them on for the fourth consecutive day between resupplies. Wool has the additional benefit of being a natural fiber, although it is also significantly more expensive than synthetics like nylon and polyester.
READ NEXT – Gear Wars: Merino Wool vs. Synthetic Base Layers
Embrace the Funk

Victoria Ketteringham photo
At the end of the day, if you’re a backpacker you’re going to stink. We all know that. This study vindicates what most of us know from experience — polyester smells horrible after a day on the trail, let alone five — and offers an interesting explanation for why that’s the case.
But thru-hikers face unique challenges compared to most clothing wearers, challenges that are beyond the scope of what this study investigated. We sweat all day. We’re typically operating with only one set of clothes for day wear, and most of us are doing laundry once a week at best. (Does jumping in a lake fully clothed count as doing laundry? Asking for a friend).
We smell of sweat, of mildew, of goodness knows what, and after a few weeks those odors get baked into our clothes and never really seem to go away, even after laundering.
So do your best — opt for wool instead of polyester, resolve to do laundry at every town stop, etc. etc. — but don’t set yourself up for disappointment by tricking yourself into believing you can outrun the funk.
Featured image: Carlie Gentry
This website contains affiliate links, which means The Trek may receive a percentage of any product or service you purchase using the links in the articles or advertisements. The buyer pays the same price as they would otherwise, and your purchase helps to support The Trek's ongoing goal to serve you quality backpacking advice and information. Thanks for your support!
To learn more, please visit the About This Site page.
Comments 1
I’m reminded of that folk song:
“If you miss the trail I’m on,
You will know which way I’ve gone;
You can smell a Hiker’s clothes,
A Hundred Miles”