The greater the weapon's size, the greater the blast wave's effective range will be, with an increase in casualties. Secondary blast injuries are caused by collapsing buildings and by timber and other debris flung about by the blast. Personnel may be hurled against objects or thrown to the ground. At sea, the shock wave produced by an underwater burst, can produce various secondary injuries. Primary burns are a direct result of the thermal radiation from the bomb.
Secondary burns are the result of fires caused by the explosion.
Flash burns are likely to occur on a large scale as a result of an air or surface burst of a nuclear weapon. Thermal radiation travels in straight lines, so it burns primarily on the side facing the explosion. Under hazy atmospheric conditions a large proportion of the thermal radiation may be scattered, resulting in burns received from all directions. Depending on the size of the weapon, second-degree burns may be received at distances of 25 miles or more. The intense flash of light that accompanies a nuclear blast may produce flash blindness at a range of several miles.