The Clean Air Act was originally passed in 1963 establishing funding for the study and cleanup of air pollution. The act was passed after several notorious air pollution incidents. In 1948 a thick cloud of air pollution formed over the industrial town of Donora, Pennsylvania and lasted for five days during which time it killed 20 people, and sickened 6,000 of the town’s 14,000 citizens. In 1952, more than 3,000 people died when a so-called, “Killer Fog” settled over London. In 1970, a stronger Clean Air Act was passed and then the EPA was created that same year and was given the role of enforcing the Act. Since 1970, the six common criteria air pollutants have decreased more than 50%, air toxics from large industrial sources have decreased by nearly 70%, new cars are more than 90% cleaner, and production of most ozone-depleting chemicals has stopped.