We Finally Know What Caused London’s Mysterious Killer Fog In 1952

In 1952 a fog descended on London, killing many of the capital’s residents in one of the most lethal atmospheric events in history.

The mysterious fog killed an estimated 12,000 people as well as causing 150,000 hospitalisations and thousands of undocumented animal deaths during the four days before it lifted, from December 5 to December 9, 1952.

Although the Clear Air Act was passed in response to the tragedy, with scientists recognising dangerous levels of sulphur dioxide released by coal burning in the atmosphere, the killer fog has since baffled scientists.

According to Business Insider, new research from Texas A&M University examining atmospheric levels in China has finally solved the mystery.

Dr Renyi Zhang, leader of the research team, said:

Our results showed that this process was facilitated by nitrogen dioxide, another co-product of coal burning, and occurred initially on natural fog. Another key aspect in the conversion of sulphur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process.

Natural fog contained larger particles of several tens of micrometres in size, and the acid formed was sufficiently diluted. Evaporation of those fog particles then left smaller acidic haze particles that covered the city.

With pollution in major Chinese cities reaching worrying levels, Zhang hopes understanding the killer fog in London will aid the efforts to clean up China’s atmosphere.

He said:

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.

The government has pledged to do all it can to reduce emissions going forward, but it will take time.

Let’s hope they can learn from our mistakes.