This is the right answer. When I think about it, spaceship crew would probably have to shave or depilate their whole bodies, to spare work for the air filters. When I see the amount of hair two people deposit in a household, a whole crew is going to shed an awful lot.

Arthur C Clarke would just make full-body hairlessness a common practice amongst spacers :P

While it is presumably implied, it could possibly be noted that space clothing should generally be fluffless.

Good, but maybe should be less about dirt and more about the BIOHAZARD the crud/stains/etc represent. You can sanitize a toilet seat. Less so with cabin seats you spend hours in. FedEx-ing a new chair in involves rather a lot higher shipping fees. And disposal fees.

Another important point: without underwear, fecal and urine microparticules will be sent floating around, which is bad for lungs.

@Eth nobody should discount the true horrors of flatulence in microgravity.

No one mentions the smell? besides flatulence, body odor gets really bad from the armpits and genitals without clothing. I would think this becomes even more pronounced in confined spaces.

@Eth Considering that urine is (almost) sterile, I seriously doubt that. And you being half wrong already doesn't inspire confidence in the truth value of the other half.

@hamncheez Have you ever been to a nudist place? That claim is just ridiculous. Obviously smell is a problem in confined spaces, but that has nothing to do with clothes.

@Ruadhan: so Arthur C Clarke and Hugh Hefner have more in common than we thought

Clothes absorb sweat and some are even made with antibacterial materials which will further reduce odours.

@Nobody just because urine is sterile doesn't mean it's perfectly okay to inhale it. I'm pretty sure you don't want most of these things in your lungs. Even though urine is ~95% water (probably more for well-hydrated spacegoers), don't discount the deleterious effects of that tiny remaining fraction.

@DoktorJ Your lungs are perfectly capable of dealing with stuff like that. Think of the amount of fine particulate matter that you breath in. In particular, the topmost thing in that list, urea, is so harmless (see Wikipedia) that it was introduced by our chemistry teacher by showing us a bottle containing it and asking for volunteers who wanted eat a piece. The second and third thing in the list form a compound together that is commonly called "household salt". And so on...

@deed02392 Absorbing sweat is not a good thing. If it evaporates, it stops maturing i.e. the smell doesn't become worse. If it's absorbed and kept at body temperature (as in wet clothes) then it really starts to stink after a short amount of time. And you have got that stuff called "hair" in your armpits and around your genitals that is designed on purpose to evaporate sweat.

@Nobody You're right that the biggest danger is fecal microparticles, much more than urine, especially as it is full of bacteria - you really, really don't want that stuff in your lungs. I suspect it may also contaminate surfaces or (if there is) exposed food, but breathing it is probably the worst. Especially as flatulences will throw them around, so there will be much more of those than urine floating around in the first place. Still, breathing urine doesn't seem that good an idea either.

@Eth Fecal matter is dangerous, that is true. But not in that way. Search for "mammalian excreta" on fda.gov/food/guidanceregulation/… which regulates how much contaminants food may contain. Cocoa beans for example (which as chocolate are consumed in relatively large amounts) may contain up to 20mg/kg feces. Now compare this to the amount that may or may not be contained in air that unintentionally leaves the anus (something that can be prevented and is already not socially tolerated).

@Eth Or in more graphic words: It's perfectly acceptable (according to FDA) for a bar of chocolate to contain that all the feces that are on the underwear of a disgusting person (seriously, if your underwear becomes stained, you are doing it wrong). Calculation: According to FDA regulations, a 100g bar of chocolate with 50% cocoa would contain about 1mg of feces, and 1mg of feces would be about the same as 1mm^3 if we suppose the same density as water (which is a sensible rough estimate). 1mm^3 is enough to leave a visible stain on white underwear I would assume.

nasa has already used cockroaches to clean air filters in space by eating human skin trapped in air filters.

@steverino, sounds interesting, but you wouldn't want cockroaches everywhere.

@Yakk Metaphorically speaking, you do. But yeah. The reference is more to give a perspective. The feces content of road dust would be more directly comparable. Feel free to search for numbers.