What is it about that event that should have people worried? December 5, 1952 was a day that was really no different from any other day in London, except that it was a little on the cool side as a result of a stretch of colder weather that had been blanketing the region for almost a month.

Being the bustling metropolis that it was, there was an ever-present smog drifting above the heads of the city’s approximately 8 million inhabitants, nothing that was considered out of the ordinary for a major urban centre accustomed to pea-soup fog and reliant on the industrial manufacturing that made up nearly 50% of its economy at the time.
On this day, unbeknownst to everyone, things were going to be different. The London fog, usually only a minor annoyance at the worst of times, suddenly developed some teeth.

Fog, smog, and now teeth? How does that all come together? What Londoners-most of whom were burning coal in their home furnaces round the clock because of the cold snap-did not know was that above them a temperature inversion caused by a high pressure system forcing air downwards was underway, causing the air 1000 feet above their Harris tweed walking hat-adorned heads to be warmer than the air at ground level.
All of that coal being burned and the resulting dense smoke it created was billowing from thousands of chimneys and being released into the atmosphere, except that the inversion trapped the smoke and mixed it in with the toxic fumes being generated by the many London factories with their massive smokestacks.

Over the span of four days, a 30-mile stretch of unbreathable smog blanketed London from the ground up. The air was turned a putrid yellow and was rank with the stomach-churning odour of rotten eggs, a result of sulphur particles mixing with a smog so dense it almost turned day to night.
Crime rates jumped as thieves took full advantage of the reduced visibility to pick a few extra pockets, rob merchants who chose to close up shop early, and ransack vehicles abandoned on the streets. Air traffic was grounded.
As conditions worsened those that braved a walk through the strange brew (or brisk run in the case of some of the morally-challenged miscreants) would arrive at their destination wheezing, coughing, and covered head-to-toe in a black veil of slimy sediment, as if someone had dumped a bowl of watered-down coal soup over them. It was disgusting. And deadly.

Within hours of what is now referred to as the Great Smog beginning, Londoners began dying. Reports estimate 4,000 people lost their lives between December 5 and December 9, 150,000 had to be hospitalized, and a further 12,000 people eventually passed away as a direct result.
It is said undertakers were having difficulty keeping up with the sudden surge in the demand for coffins, and many a family pet, bird, and wild animal were also killed. The smog was finally blown away from London and out over the North Sea, but not before the damage was done.
While all of this is a bleak black mark on the city’s past, a group of researchers from Texas A&M University have only recently been able to pinpoint exactly what caused this environmental crisis to be such a deadly one.

In a recent study published by the Proceedings of the National Academy of Sciences, the team discovered similarities in what they now think caused the Great Smog and environmental issues currently being faced by China. Their conclusion: Londoners were essentially breathing acid rain.
Back in 1952 the coal being shovelled into furnaces in homes and factories across London released sulphur dioxide. From that, sulphuric acid particles formed. Sulphate was present, thanks to nitrogen dioxide also being on the scene as a result of the chronic coal burning.
All of these compounds then mixed together in the naturally damp and foggy London environment and presto-droplets of sulphuric acid were created and sent hitchhiking across the city where unsuspecting residents breathed them in and they became a lung’s knife-wielding passenger.
There were steps taken in the wake of this, and after a little feet dragging on their part British Parliament passed the Clean Air Act of 1956. The Act banned emissions of black smoke in urban areas and provided subsidies for residents and manufacturers to convert to safer, smokeless fuels.
Today, London is fighting a battle against nitrogen dioxide, and estimates put the city’s yearly death toll from this ‘invisible pollution’ at 9,000 people. Maybe the next Great Smog might not be as smelly as 1952’s, but the results may be just as deadly.