Cotton kills.But what if the garment is only 23 % cotton with the rest being polyester and acrylic?I bought some Arctex long underwear and was wondering if its OK to wear it outdoors or should I leave it for chilly nights in the house.Thanks,Dave

It will be fine; go ahead and use it. That's just enough cotton to improve the feel.

I have always wondered, USGI issue fatigues, including the M-43 and M-65 field jackets, plus the state of the art insulated underware of the time, used to be just about 100% cotton (to the best of my knowledge). Uncle Sam was well known for having his troops playing out in the cold and wet for hours and day and weeks, why didn't we all freeze to death???

Is that brand Arc'Teryx?

If so, that canadian maker makes top-notch outdoors gear. I think that 23 % cotton is not a problem, I like a blend of polyester and cotton. Cotton makes the garment more comfortable.

If I am seriously worried of hypothermia (snowshoeing in the backcountry), I would wear 100 % body-hugging polypropylene as base layers.

The problem ain't hypothermia per se, its flashburns as the polyproplyne melts onto you. Cotton is only a problem if its gets wet. In hypotherma conditons taking your time and avoiding high areobic situations is your primary defence.

Polyprolene might melt when on fire, I have not verified this, but I don't really see how it can happen unless I throw myself in a fire of some kind.
It's the best moisture wicking material for severe weather, and works great as a base layer in harsh condition.

Thanks for the replies and for putting me at ease.
I already have some polypro underwear but figured on using the Arctex (by Morgan Mills) for day to day wear and saving the polypro for below zero weather, under the Arctex.