My work uniform is mostly wool. I wear silk under, add wool for real cold days. Last couple of weeks, the high was 28 to 31. Started work a couple of days, -8,-2 . Was soaking wet with sweat but still warm. (Heat wave today). Our work jacket is nylon , my jacket is full of burn holes from flares. I hear they want to change from wool, I hope not. KOM makes a wool jacket I was wanting to wear and get rid of the expensive junk we wear now. But it is the Brass in Phoenis that makes the rules. We are 7000'+ higher than them. Wool when it gets bad!