Mens Hi Vis Viz Two Tone Jogging Bottoms Combat Trousers Workwear Joggers

Are these fire resistant?

I’m normally 38 but I spend the day bent over. What size? don’t want to be cut in half

I’m normally a size medium men’s in trackies and 32’ in jeans so should I order a32’

Are the knees the thicker material or the thin polyester? Have bought pair like these before but the knee fabric was really thin - thanks