Tragic, of course. SCBA, anyone? Or at least some education and a hand-held monitor (available from many sources)?
There are great differences between CO and CO2, the latter being a simple asphyxiant (toxic by displacing oxygen from the breathing atmosphere, the first being a systemic asphyxiant with properties of binding more strongly to hemoglobin than oxygen resulting in severely decreased tissue oxygenation particularly to the brain and heart. Both deadly in the wrong circumstances, just by different methods. CO2 has other toxic effects such as vasodilatation, increased rate and depth of breathing, etc. Seen a case where a whole USAF aircrew was poisoned from offgassing of "dry ice" (CO2 sublimates -- goes from solid form directly to gas -- which had been used to preserve fresh foods and wss stored in the back of a transport airplane which had to make an unexpected overnight stop on the way. Sealed plane, confined space, luckily the crew became ill before starting a new flight and so survived.
N2 being a "natural" chemical is also a simple asphyxiant. Got to be some other way to make ice cream that doesn't use it. Nature can and will do it to you,Ddespite all the chemophobic hype about "anthropogenic" toxicants. Brown recluse spider vemon and their ilk, black widow spider venom, rattlesnake and all other species of poisonous snake venoms, the 8 classes of toxic mushrooms, etc., etc. are all "natural". Anyboby want to take a raft trip down a certain beautiful river, dig up some "wild onions", and die ofwater hemlock poisoning?
Alan H. Hall, M.D.