"In a full-scale nuclear war the most destructive danger will be fire storms. These will kill everybody, even in very deep shelters, either by heat or by lack of oxygen, whichever operates the more quickly. Fire storms will turn the oxygen in the air into carbon monoxide which is poisonous and heavier than air so that it will seep into underground shelters. All the Authorities know this, but shelters and all forms of civil defence are an attempt to conceal the knowledge for the public."