Some of these people would be injured by the pressure of the explosion, while most would be exposed to injuries from collapsed buildings or flying shrapnel; most buildings within a 0.5 mile (0.8 km) radius of the detonation would be knocked down or severely damaged. If you somehow survive all of that, you still have to deal with radiation poisoning and nuclear consequences. However, for more information on the current state of nuclear weapons in the world, including the scale of bombs, you can visit the Nuclear Notebook in the Bulletin of Atomic Scientists. Since large doses of radiation of approximately 20 roentgen or more (see radioactivity note) are needed to produce developmental defects, these effects would likely be limited to areas of heavy local rainfall in nuclear warring nations and would not become a global problem.
Radioactive fallout has occurred all over the world; for example, people have been exposed to iodine-131 from atmospheric nuclear tests. As the nuclear energy sector continues to grow, international rhetoric around nuclear war intensifies and the ever-present threat of radioactive materials falling into the hands of dangerous people persists, many scientists are working hard to find the best way to protect organs humans from the harmful effects of high-energy radiation. The 1963 Limited Nuclear-Test-Ban Treaty ended atmospheric testing for the United States, Great Britain and the Soviet Union, but two major non-signatories, France and China, continued nuclear testing at a rate of approximately 5 megatons per year. There are three very different versions of the precipitation pattern of this test, because rainfall was measured only in a small number of widely spaced Pacific atolls.
The destructive effects of explosions extend miles from the point of detonation of a typical nuclear weapon, and the lethal consequences can cover communities hundreds of miles downwind of a single nuclear explosion. This form of radioactive contamination is known as Nuclear Rain and represents the primary risk of exposure to ionizing radiation for a large nuclear weapon. Whether because of the escalation of a limited nuclear conflict or as a large-scale attack, all-out nuclear war is still possible as long as nuclear nations have hundreds or thousands of weapons pointing at each other. A nuclear war would produce enormous quantities of ozone-consuming chemicals, and studies suggest that even modest nuclear exchange would lead to unprecedented increases in ultraviolet exposure.
For high-altitude nuclear explosions, these electrons are captured in the Earth's magnetic field at altitudes between twenty and forty kilometers, where they interact with the Earth's magnetic field to produce a coherent nuclear electromagnetic pulse (NEMP) that lasts approximately one millisecond. However, groundwater supplies, such as aquifers, would initially remain uncontaminated in the event of a nuclear fallout.