Researchers Reveal How Chemicals Combined to Form Acidic Haze that Killed 12,000 in 1952 in London

In 1952, a mysterious fog swept through London, blanketing the city in a dense layer of pollutants that killed thousands of people and animals and made it difficult to breathe for days. While the exact cause has long remained unknown, an international team of researchers now says its solved the mystery – and the same air chemistry can be seen today in China and other areas.

In a new analysis, the researchers have pinpointed the chemical processes that combined with natural fog as a result of coal burning, eventually creating a deadly acidic haze that turned the sky completely dark. When the fog first rolled through in December of 1952, residents took little notice; fogs have long enveloped the city. But in the days to follow, visibility was reduced to just three feet in some areas, transportation was shut down, and thousands of people suffered from breathing problems. After the devastating event, it was thought that at least 4,000 people had died, along with thousands of animals, and more than 150,000 people were hospitalized.

'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 sulfur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process. 'Natural fog contained larger particles of several tens of micrometers in size, and the acid formed was sufficiently diluted. ‘Evaporation of those fog particles, then left smaller acidic haze particles that covered the city.’ According to the researcher, a similar chemistry frequently occurs in modern China, which hosts 16 of the world’s most polluted cities.

Read the full article @ Daily Mail