Free Armageddon Science by Brian Clegg

over once the dust had settled.
    Death did not cease in the minutes following the initial explosion. Radiation sickness would nearly double the initial death toll to well over 100,000 people during the subsequent year. That was out of a population of 350,000. Some have put the eventual total at double this. Although the explosive power of nuclear bombs is terrible, this is the truly terrifying aspect of such weapons: the silent, invisible, deadly action of radioactivity. From the very first days of working with radioactive materials, it became clear that the remarkable power of these elements was a two-edged sword. One of the earliest radioactive elements discovered was radium—and this element would claim the life of its discoverer, the double Nobel Prize winner Marie Curie, born Maria Sklodowska.
    Working with her husband, Pierre, Marie Curie was studying pitchblende, a mineral found in north Bohemia that contained uranium. Pitchblende was mined near what’s now Jáchymov in the Czech Republic, and after uranium had been extracted from the ore to be used to color pottery glazes and tint photographs, the residual slag was dumped in a nearby forest. Without the uranium, the pitchblende proved still to be radioactive—in fact, whatever the other radioactive material in pitchblende was, it was much more radioactive than the uranium itself.
    Marie Curie wrote to her sister Bronia that “the radiation that I couldn’t explain comes from a new chemical element. The element is there and I’ve got to find it! We are sure!” After working through tons of the pitchblende slag, painstakingly processing the material by hand, the Curies identified two new elements in the remaining material—polonium and radium. Radium, named for the Latin for “ray,” was finally isolated in 1902 in its pure metal form and proved to be the most radioactive natural substance ever discovered.
    Although Marie Curie lived until 1934, her death at the age of sixty-seven from aplastic anemia is almost certainly due to her exposure to radioactive materials, particularly radium. To this day her notebooks and papers have to be kept in lead-lined boxes and handled with protective clothing, as they remain radioactive. Marie Curie was the first victim, but radium would go on to kill others. It was seen in the early days after its discovery as a source of energy and brightness, it was included in toothpastes and patent medicines—it was even rubbed into the scalp as a hair restorer.
    The application of radium that would bring it notoriety and would emphasize the dangers of radioactivity was its use in glow-in-the-dark paint. Unlike modern luminous paint, which has to be activated by bright light, storing up energy to release later, radium glows constantly from its natural radioactive energy. It was frequently used to provide luminous readouts on clocks and watches, aircraft switches and instrument dials; its eerie blue glow was seen as a harmless, practical source of nighttime illumination. It was only when a number of the workers who painted the luminous dials began to suffer from sores, anemia, and cancers around the mouth that it was realized that something was horribly wrong. The women workers would regularly bring their paintbrushes to a point by licking them. This left enough radioactive residue in their mouths to cause cell damage. Eventually more than a hundred of the workers would die from the effects.
    These weren’t the first deaths from radiation. It has happened as long as human beings have been around, without realizing the cause. Natural radiation levels vary hugely from place to place. Denver, for instance, has a significantly higher background radiation level than New York. Some rock types, notably granite, release significantly more radiation than others, particularly when naturally released radon gas builds up in houses. Throughout history, background radiation has triggered cancer in handfuls of individuals. But this is as nothing