Mystery Of The Historic 1952 London Killer Fog Finally Resolved, Scientists Claim

The cause of the killer fog that covered London for five days in 1952 has been finally solved. This mysterious fog blanketed the city of London and killed thousands of residents.

An international team of scientists analyzed the killer fog. They found that the chemical processes that mixed with natural fog because of coal burning created a deadly acidic haze that turned the sky completely dark. This air chemistry also occurred in China and other regions, according to Phys.Org.

The findings of the study were published in the current issue of the Proceedings of the National Academy of Sciences (PNAS). It was led by Renyi Zhang from Texas A&M University and a distinguished professor, Harold J. Haynes, the Chair of Atmospheric Sciences and Professor of Chemistry, graduate students Wilmarie Marrero-Ortiz, Yun Lin, Yixin Li, Jeremiah Secrest, Bowen Pan and Jiaxi Hu and researchers from Florida, California, Israel, China and the U.K.

Mail Online reports that in December 1952, the city of London was enveloped by fog. This caused people suffering from breathing problems and transportation was shut down. After the five-day harmful event, it was reported that 4,000 people died together with thousands of animals and over 150,000 people were hospitalized. Later, it was reported that more than 12,000 people of all ages died. The cause of the killer fog was unknown for 60 years.

Recently, the team of researchers finally unraveled the mystery of the killer fog, conducting laboratory experiments and atmospheric measurements. Zhang explained that sulfate was a big contributor to the fog and sulfuric acid particles were formed from sulfur dioxide released by coal-burning for power plants and residential use and other means.

On the other hand, the conversion of sulfur dioxide into sulfuric acid was unclear. Zhang further explained that the results of the study showed that this process was facilitated by nitrogen dioxide, which is a co-product of coal burning, and occurred initially on natural fog.

He added that the another key aspect in the conversion of sulfur dioxide to sulfate is that it produces acidic particles that subsequently inhibits the process. The natural fog with bigger particles of several tens of micrometers in size and acid that was formed was sufficiently diluted. Zhang then concluded that evaporation of those fog particles then left smaller acidic haze particles that enveloped the city of London.

The researchers thought that they have solved the 1952 London fog mystery and given China some ideas of how to improve its air quality. The reduction in emissions of nitrogen oxides and ammonia is likely effective in disrupting this sulfate formation process, according to Zhang.