The Big Idea: NAS Team Solves Mystery of the London Killer Fog


The environment has been an on-again-off-again issue, but lately with the seemingly never-ending debate on climate change, there has been a real awareness rising up about our planet. What I find odd is that the world has been telling us for decades “You need to pay attention to me because this planet, presently, is the only home you got.” Before the concern about ice caps, the concern about carbon emission, and before the concern about changing water temperatures, the world was facing a different concern: Killer Fog.

Yes, you read that right. Killer Fog.

Street Covered In FogThis little nudge from Planet Earth happened in December 1952. It was a particularly cold morning and as this was a time before central air conditioning and climate control, coal fireplaces were doing their best to keep London warm. By midday, the clear skies were swapped out with an unexpected fog, and the thin veil of moisture interacted with the soot pouring from chimneys and smokestacks of varying sizes. The reaction created a thicker, heavier fog comprised of pollutants—mainly sulfur—that covered London for five days, causing breathing problems and killing thousands of residents.

When the fog first arrived, London residents didn’t really give it much notice because it appeared no different from the familiar “pea soupers” that have swept over Great Britain in the last thousands of years. However, a high-pressure system stalled over the city, preventing the smoke to dissipate properly. With so much coal soot in the air, conditions deteriorated over the next few days, and the sky became so dark that sunlight was blocked. Visibility was reduced to only three or four feet in parts of the city. All transportation was shut down. Tens of thousands of people had trouble breathing. By the time the fog lifted on December 9, at least 4,000 people had died and more than 150,000 had been hospitalized.

The 1952 Killer Fog led to a Clean Air Act in 1956. This particular event is still considered the worst air pollution event in European history. The exact cause and nature of the fog remained mostly unknown for decades, but an international team of scientists believes that the mystery has been solved. While people have known that sulfate was a big contributor to the fog, it turned out that the sulfate reacted with some elements in the air and created sulfuric acid. Droplets of sulfuric acid were discovered in the fog, and these were formed from sulfur dioxide which had been released by coal burning in residential use and power plants, and other means. The ongoing mystery was how sulfur dioxide turned into sulfuric acid. Their results showed that this process was facilitated by nitrogen dioxide—another co-product of coal burning—that occurred initially on natural fog and it was just the right combination for the two chemicals to react and form sulfuric acid. This particular chemical mix doesn’t occur very often, but when it does it is hard to miss. Studies in China have shown that some of their city pollution is similar to what happened in London. Why the Killer Fog has not returned is a bit of a mixed blessing. Over Chinese cities there is ammonia in the atmosphere, released from fertilizer manufacturers. That ammonia in the atmosphere neutralizes the fog, preventing it from turning into sulfuric acid. That’s good.

But there’s ammonia in the atmosphere. That’s bad.

This research into the Killer Fog was published in Proceedings of the National Academy of Sciences on October 9, 2016, and it suggests that the same air quality that happened then is happening today in China and other places.

It’s a warning. From 1952. We really should pay attention to it.



shurtz.jpgA research physicist who has become an entrepreneur and educational leader, and an expert on competency-based education, critical thinking in the classroom, curriculum development, and education management, Dr. Richard Shurtz is the president and chief executive officer of Stratfdord University. He has published over 30 technical publications, holds 15 patents, and is host of the weekly radio show, Tech Talk. A noted expert on competency-based education, Dr. Shurtz has conducted numerous workshops and seminars for educators in Jamaica, Egypt, India, and China, and has established academic partnerships in China, India, Sri Lanka, Kurdistan, Malaysia, and Canada.




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