A long time ago, in 1991 there was this factory that would pump smoke out in the air. One day this factory pumped out too much smoke, and the smoke in the air would combine and make clouds. The clouds would block the sun from hitting the town. When there is no sun hitting the town it gets cold because the sun creates heat, no sun no heat. They did not know how to make the pump stop so the smoke kept going and when there is too much smoke the air quality can get very bad for us humans.