The London Great Smog in 1952 was as mysterious as it first appeared. How the deaths came was just as mysterious. Scientists have finally uncovered the reason behind the 12,000 deaths during the Great Fog.
An investigation on China's air pollution has lead to unraveling the mystery of deaths 64 years ago and to a place 5,058 miles away.
By N T Stobbs, CC BY-SA 2.0, Link
So what makes the mist that covered the city of London in 1952 deadly?
According to Renyi Zhang of Texas A&M University and his team, the answer is sulfate. It's an elusive compound that can be formed in a dense, coal-rich, dewy air of nitrogen dioxide and sulfur dioxide.
Nitrogen dioxide's toxicity will depend on the duration of exposure. It's a pollutant but it's not highly toxic.
Sulfur dioxide can only be toxic and life threatening in high levels of exposure.
Exposure to nitrogen dioxide and sulfur dioxide alone will cause health degradation but gradual death. In the case of the Great Smog, there were 4,000 premature deaths after the fog lifted and 100,000 went ill. The deaths might have had caused by something else other than just nitrogen dioxide and sulfur dioxide. It confirms strongly that another compound might have caused those deaths.
View from Park Hyatt Shanghai, 1998, BriYYZ
Now we have a strong case against the involvement of sulfates. But still, how did it poison the citizens?
When the acidic dew evaporated, it left an even bigger acidic particle in the haze. The rain might have went down, but it was what the people were breathing in that caused their deaths. Breathing comes naturally after all. That was the easier yet tragic part that lead to their deaths.
Zhang concluded, "We think we have helped solve the 1952 London fog mystery and also have given China some ideas of how to improve its air quality. Reduction in emissions for nitrogen oxides and ammonia is likely effective in disrupting this sulfate formation process."
Zhang and his team published their work in Proceedings of the National Academy of Sciences