What was the primary cause of the London Fog of 1952?

Cold weather in December 1952 led London residents to burn large amounts of coal for heat. The coal smoke and pollutants accumulated near the ground because a temperature inversion kept cooler air—and the pollution within it—trapped below warmer air above. Therefore, the best answer is B: cold air increased coal use, and the smoke was trapped close to the ground by a temperature inversion.

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