I should probably let this one drop, but what the heck. Nothing I have found regarding CS , or CN indicate that it can be fatal. Poison ivy, on the other hand, can be. I have been exposed to both CN and CS (thankfully I got to skip DM), they hurt, but is it a short term hurt. Unlike the blisters in the lungs that poison ivy can cause. I would hope that you (and others) will skip burning poison ivy in the future...