At present, very little radioactivity can be detected from weapons tests conducted in the 1950s and 1960s in the environment. The United States was the first to conduct a nuclear weapons test on the ground in southeastern New Mexico on July 16, 1945. Following this, hundreds of aerial explosions occurred around the world, releasing various isotopes into the atmosphere. These isotopes can affect people through external exposure (radiation outside the body) or internal exposure (radiation inside the body). Some radioactive materials remain for a short period of time, while others remain for an extended period of time.
Due to some of the durable isotopes released during weapons testing, a small amount of radioactive fallout still exists in the environment today, exposing people to radiation. For example, the bomb dropped on Hiroshima caused a total devastation of five square miles, with almost every building destroyed or damaged. Fortunately, radiation levels have dropped significantly and are now equivalent to background levels expected anywhere on Earth. The parts devastated by the bomb have been rebuilt and reoccupied.
Most nuclear powers have conducted hundreds of nuclear tests in remote parts of the world over several decades. But what is the current status of these test sites? Despite warnings, the most powerful nuclear test, the Cannikin nuclear test, took place on November 6, 1971. Studies and evaluations have estimated that cancer deaths due to global radiation doses of nuclear test programs in the atmosphere of five nuclear-weapon States amount to hundreds of thousands. The magnitude of initial damage is directly related to the power or performance of the nuclear warhead; however, any nuclear explosion will leave some kind of legacy long after it has been performed.