On December 4, 1952, the weather in London, UK, suddenly began to get cold. Fuel use rapidly increased throughout London. At that time, both homes and industries were using coal as fuel. The smoke from burning coal was emitted into the atmosphere without filtration and the emitted smoke combined with the thick fog to form smog. About 4,000 citizens died from respiratory disorders and suffocation in the first three weeks. After that, an additional 8,000 people died from chronic lung diseases. The London smogs served as a wake-up call about the dangers of air pollution not only in the UK but also in countries around the world.