I bought a mat that I thought would kill me before it was done with all of its out-gassing! Holy cow, it was strong! It gave me a headache every time I used it. The brand was Olfa, and I didn't give it a sniff test before I bought it because I didn't have that problem with any of my other mats. It took a very long time for the outgassing to not bother me, time and air took care of it.