The Great London Smog of December 1952 lasted five days and killed up to 12,000 people. The smog developed primarily because of extensive burning of high-sulfur coal. The health effects were both immediate and long lasting, with a recent study revealing an increased likelihood of childhood asthma development in those exposed to the Great Smog while in utero or during their first year of life. Subsequent pollution legislation—including the U.S. Clean Air Act and its amendments—have demonstrably reduced air pollution and positively impacted health outcomes. With poor air quality events like the Great Smog continuing to occur today, nurses need to be aware of the impact such environmental disasters can have on human health.