At present, very little radioactivity can still be detected from weapons tests in the 1950s and 1960s in the environment. The United States conducted the first nuclear weapons test on the ground in southeastern New Mexico on July 16, 1945.Between 1945 and 1963, hundreds of aerial explosions occurred around the world. Some of these isotopes could affect people through external exposure (exposure to radiation outside the body), while others could affect people through internal exposure (exposure of a specific internal organ to radiation inside the body). Some radioactive materials remain only for a short period of time, while others remain for an extended period of time.
Because some of the isotopes in the aftermath of weapons testing were of the durable type, a small amount of radioactive fallout remains in the environment today, and people can continue to be exposed. The bomb caused a total devastation of five square miles, with almost every building in the city destroyed or damaged. Today, radiation levels have dropped significantly and are approximately equivalent to background levels expected anywhere on Earth. The parts devastated by the bomb have been rebuilt and have now been reoccupied.
To this end, most of today's nuclear powers have conducted hundreds of nuclear tests in several remote parts of the world, taking place for decades. But, you may be wondering, given that nuclear testing has largely ceased for most nuclear powers since the late 1990s (North Korea is the exception), what is the current status of these test sites? The warnings fell on deaf ears; the most important nuclear test, the Cannikin nuclear test, took place on November 6, 1971.Some studies and evaluations, including an evaluation by Arjun Makhijani of the health effects of nuclear weapons complexes, estimate that cancer deaths due to global radiation doses of nuclear test programs in the atmosphere of the five nuclear-weapon States amount to hundreds of thousands. While the magnitude of the initial damage is directly related to the power or performance of the nuclear warhead, any nuclear explosion will leave some kind of legacy long after the test has been performed.