By my understanding, fallout is less a function of the explosion being nuclear and more of how the bomb is detonated. The Tsar Bomba was an air-burst. By keepin

By my understanding, fallout is less a function of the explosion being nuclear and more of how the bomb is detonated. The Tsar Bomba was an air-burst. By keeping the fireball in the air, less vaporized material from the ground is kicked up into the debris cloud from the blast. Both air bursts and ground bursts generate fallout, but a ground burst will generate nastier, localized fallout, and more of it. This is my speculation, but I suspect another reason for the relative lack of fallout from the Tsar Bomba was related to its yeild. To get a particularly large yeild from the materials available, the bomb is going to have to be as efficient as you can get it. All things equal, a more efficient system generates less waste. Or the design the article could simply be referring the bomb's parachute system, which helped keep the blast in the air.