In early December, London experienced a severe weather phenomenon known as a cold spell, which coincided with high levels of air pollution. The combination of fog and fog created a dense layer of smog that descended upon the city, drastically reducing visibility and contributing to a multitude of health issues among the population. This event persisted for approximately four days, during which normal activities ground to a halt. Public transportation services were severely impacted, and citizens were advised to stay indoors as the air quality deteriorated sharply. The burning of coal for energy and heating purposes contributed significantly to the pollution levels, making the situation more dire. The Great Smog was characterized by its noxious mix of sulfur dioxide, smoke, and other particulate matter, which proved particularly harmful to vulnerable groups such as the elderly and those with pre-existing health conditions. 

As the smog enveloped the city, it attracted national attention, leading to public outcry over air quality and city planning. Emergency services struggled to respond to the increased number of people suffering from respiratory problems. Hospitals were overcrowded as patients flooded in with symptoms of respiratory distress. The severity of the situation prompted scientists, health officials, and government bodies to assess the extent of fatalities linked to the smog, resulting in an alarming estimate of around 4,000 deaths within a short period. The impacts of the Great Smog highlighted the urgent need for regulatory measures to manage air quality in urban areas effectively, leading to significant changes in environmental policies in the years that followed.