Firestorms during a pole shift can temporarily depleat Oxygen in the locale, creating suffocation problems for those in the open air. There is some evidence that some of the Mastodons flash frozen in Siberia died of suffocation. The Zetas have stated that those in shelters Need Not Worry. To be on the safe side, there are various Sources of oxygen replenishment. Indoor Algae Ponds are more than an excellent protein rich source of food, they are oxygen generators. Spare-Air is inexpensive.