Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that developed nuclear weapons tested them. Since the dawn of the atomic age in July 1945, nuclear weapons have been tested on more than 2,000 occasions – in the atmosphere, underground and underwater. The toll on human health and the environment has been staggering. Today many of us carry in our bodies radioactive substances from the fallout of nuclear testing, increasing our risk of developing cancer. Much of the Earth’s surface has been contaminated at some point with radioactive particles. Nuclear testing enables nations to increase the lethality of their nuclear forces. Length 20:00.