Yes, agree with Dennis. Woodstock is concerned that you not have too much air when you have active flame. Added air during the burning of the coals is not going to harm the cat. At least it didn't when I burned my Fireview, with the ceramic cat. Only possible problem would be if you had a really strong draft and got some fly ash through the screen and into the cat...might have to brush off the cat. The newer stainless ones have smaller honeycomb....has anyone had a problem with that? But it's not going to harm the cat.