Causality 18: The Fog

15 September, 2017


In 1952 a fog in London left 4,000 dead in just 4 days but many more would die before the causes could be rectified. Worse than that, it had happened before and it’s happening again right now, somewhere else.

Transcript available
Chain of events. Cause and effect. We analyse what went right, and what went wrong, as we discover that many outcomes can be predicted, planned for and even prevented. I'm John Chidgey, and this is Causality. Causality is part of The Engineered Network to support our shows including this one, head over to our Patreon page and for other great shows visit today. "The Fog" In 1952 for 5 days in London England experienced what has been referred to as the killer fog. The great smog of London, the big smoke or simply The Fog. Since London's settlement and often romanticised in the novels of Sir Arthur Conan Doyle as Sherlock Holmes would make chase during foggy London evenings, London has suffered from regular, thick heavy fogs. Many of the heaviest fogs were caused by the local topography in conjunction with semi-regular anti-cyclones that inevitably led to temperature inversions. During temperature inversions a pocket of air is contained within another and are characterised by stagnant air masses that are colder than usual...air being trapped at the ground level. Such a temperature inversion formed in the London area during Thursday the 4th of December, 1952. At 3:00pm the fog began to form noticeably and workers at the dockyards, with crane operators perched high above the ground, reported by 4:00pm that afternoon, that they could no longer make visual contact with the workers at ground level and works on the docks were abandoned for the day at that point. The worst of the fog hit in the early hours of the morning of Friday the 5th of December, 1952. Visibility had decreased further until it reached a recorded minimum of only 3ft, just under 1m. All primary forms of transportation were cancelled. There are no buses on the roads and no trains above the ground, although the London Underground subway service did continue to operate. Those that were game enough to drive, had to do so by poking their heads out of the side door window, because the fog had left a slick on the windscreen that distorted what little visibility there was and that could not be cleared effectively by their windscreen wipers, leaving nothing more than a smudged slick on the windscreen. Ambulances were unable to retrieve the increasing number of people that had succumbed to the conditions. And most sick people had to make their way on foot as best they could to nearby hospitals. Some ambulances did make it through the fog, but they did so with a person leading the way through the fog ahead of the ambulance, holding a bright burning torch above their heads to show them a safe path. The smog seeped into buildings and in a particular large areas of buildings like theaters and auditoriums caused most shows to be cancelled due to poor visibility indoors of the stage or the screen. People began to notice a grey film forming on surfaces indoors as the day's progressed in the fog. The fog was reported to have an acrid stinking acidic taste and smell. It was warm to the skin. Some reporting that it felt like a warm soft blanket. At night the street lighting was unable to penetrate the fog to even reach eye-height, let alone ground level. Many people that had lived through the blackouts of World War 2 years earlier during the Blitz, commented that the nights had been blacker than the blackouts of the war. The fog finally lifted Tuesday the 9th of December, 1952 lasting a total of 5 days. However on the 8th of December the government had already recorded almost 4,000 deaths as a direct result of the smog, with 100,000 reporting respiratory distress. Shortly after the incident Harold McMillan the Minister of Housing and Local Government and later Prime Minister of the United Kingdom, was insistent that had been a wholly natural disaster for which nothing could have been done to prevent it. Many Londoners had come to accept fogs in their City and this incident was the final straw. Most didn't and couldn't believe the official position and rejected that nothing could have been done. So what caused so many people to die? Sulfuric Acid particles were formed when Sulfur Dioxide combined with Nitrogen Dioxide in the water droplets of the fog. It became concentrated when the water particles evaporated during daily cycle, producing a mist of airborne acidic-oily particles. The acid when breathed in irritated, burned and inflamed animal tissues and the oil made it extremely difficult to remove. The majority of deaths stemmed from Hypoxia, most commonly referred to as suffocation, as a result of 2 primary factors. The first was excessive pus and mucus production from lung infections caused by breathing in smog particles. The second, swelling of the primary and secondary airways to the lungs causing irritation from breathing in the fog. The acids in the fog caused chemical burns in the lungs, alveoli and bronchi, leading to an immune response which in many cases escalated into Bronchial Pneumonia and Purulent Bronchitis. It's true that many of those that died in the disaster were those that were immunologically exposed, the young and the elderly and in some cases some with pre-existing respiratory conditions. So now we know why it caused so many people to die. What caused the fog in the first place? We have to go back to the beginning...for London at least. Many started by thinking it was the Industrial Revolution, hundreds of years previously. Certainly they'd been warning signs of the calamity to come. The burning of coal for heating, boiling of water for steam engines and factories, for transportation in trains and ships. They had no filtration on their exhaust outlets, and it carried with it a soot particles that reduced visibility amongst other chemicals. Since coal had been mined to fire furnaces of all sizes for hundreds of years, it had been found that some coals were both either higher or lower grades, meaning high grade coals produced more heat and less smoke, they burn more cleanly, leaving less residue when their fuel had been burnt through. Increasing demand for coal to fuel the industrial revolution played a significant role. Open fireplaces with coal and wood to burn created large amounts of soot and the vast majority of houses in London had fireplaces and the population density was so great that it was a huge contributor to this incident. Officially blame was directed to the collective individuals rather than industry, blaming the cold weather at the time and people burning more coal in their home open fireplaces for causing the disaster. And whilst technically this was the biggest contributor, it certainly wasn't the whole problem. Official fallout maps of the soot following the incident showed the largest concentrations of soot in the predominant air-direction downwind of 3 of the major coal-fired power stations in the London area at the time, being Suffolk, Battersea and Kingston. These 3 power plants were approved by the government for construction in the city over a decade earlier, with the final plant brought online in 1948, 4 years before the disaster. Interestingly the Battersea Power Station was resisted by the royal family itself, specifically taking time to write to the Prime Minister of the time expressing their concerns about introducing toxic gases into this densely populated London area. The Battersea Power Station was designed with the capacity of 400MW and when completed consumed 1,000,000 tonnes of coal each year after its final expansion. The exhaust fumes from the other power stations all used a new technology called "scrubbers," that were designed to reduce Sulfur emissions. The scrubbers used water and alkaline sprays over a catalyst of Iron Oxide which theoretically, converted Sulfur Dioxide into Sulfuric Acid, prior to emission into the atmosphere. However it proved to be ineffective in use and the system was removed from service in the 1960s although, primarily because the wastewater had been discharged into the Thames and this was actually causing significant environmental damage to the rivers ecosystem. Financially the government also contributed to the disaster in an indirect way. The British government at the time was bankrupt, and in an attempt to settle their debts they were selling the highest grade coal that Britain produced overseas, to bring in more money. At the same time they didn't want to restrict local industry that was capable of generating revenue and helping to pull the country out of debt, hence this redirection of the highest-grade of coal and lack of will to impose any restrictions on industry meant that the lower grade coal that emitted the most smoke and pollutants was all that was left for the local market, be that industrial or personal. Not only were they burning more coal than ever before, but they were burning the dirtiest coal that they had. The final contributor was the push for buses, and that was happening the world over. As part of the transition to buses and whether you believe conspiracy theories or not, the buses were unconstrained by tracks and electrical overhead wires or embedded power cables and were supposed to relieve traffic congestion (so was their sales pitch at the time.) Years later though, studies showed that there had been no improvement in traffic flow from the removal of the trams and introduction of the buses. The last electric tram was removed from service in London on the 5th of April, 1952 only 8 months before the incident. All the trams had been replaced by nearly 8,000 diesel buses. The diesel buses at the time were running on a much lower grade diesel fuel mixture than that of today. That was also higher and sulfur content. The perfect storm of events then...perhaps led to what was a huge death toll. The government had approved 3 large coal-fired power stations to be built in central London. Ineffective scrubbers on the power stations didn't significantly curtail their pollution. The post-war fallout had left the country in debt with a government drive to push for industrial production not to be held back. Selling high-grade coal to get the country out of debt, left only low-grade coal locally. Electric trams were removed in favor of higher polluting diesel buses. Cold weather at the time meant more homes burnt more coal to stay warm and a temperature inversion trapped a cold air mass in the Thames Valley for nearly 5 days. Most disturbingly however it had already happened before. In 1880 an estimated 2,000 people had died due to excessive smoke in London under a similar temperature inversion. A parliamentary committee was formed at the time and reported with recommendations to better control local industries spurred on by the Industrial Revolution from spewing smoke into the local air. These were mostly ignored and eroded over subsequent decades, as industry pushed forward. Starting on the 27th of October, 1948 and lasting 4 days in Donora, Pennsylvania during the winter, the yellow smog was so thick that you couldn't see your hand at the end of your arm. The smog was described as a deep yellow saffron colour and made your eyes burn and water, and 20 people died and 7,000 became sick as a direct result of that smog. The Donora incident specifically directly drove the 1950 International Air Conference. The conference called for more smoke control in living areas and better regulation of industry. In the United Kingdom the Housing Minister had blocked the recommendations following the conference. With a bit of further thought and researched through, historical records it became clear that London's fogs are in fact the result of industrial development since the 1800s but even before in medieval times, deforestation and fires burning in the London area, began the ethos that London was a foggy area. It isn't and it wasn't really at least not especially. Certainly the topography helped to amplify the effects of air pollution, but before those times there were no such fogs recorded of that density or regularity. So the truth is that we (human beings) created the fogs of London. Those fogs were written about by Sir Arthur Conan Doyle and painted by Monet, and they were our own doing. The final death toll 11 months following the incident, the official investigation confirmed that yes 4,000 had died during the immediate timeline of the incident, however a further 8,000 died from complications directly related to the fog with a timeline ending in late February some 2 months following the event. 4 months after the report was released it was amended down by that 8,000 deaths claiming those that had died after the fog had cleared were in fact victims of an influenza epidemic instead and not the fog. A counterclaim by the World Health Organization report that tracked down the detailed causes of death during that period in January and February, determined that only 457 people out of those 8,000 were in fact as a result of influenza. As a direct result of this incident the Clean Air Act was brought into force in 1956. The primary components of the Act included the establishment of smoke-free areas which is...effectively alignment with the intentions of the 1950 International Air Conference, and provided subsidies for households that converted to cleaner fuels for heating and cooking including gas and electricity. The effects of the Act weren't immediately felt for nearly 10 years, and subsequent fogs in 1956, 1957 and 1962 claimed a further 1,500 lives. It has been amended and extended several times since, however it is widely considered to be a landmark in environmental protection legislation and was a turning point in our modern world in how we manage our air pollution. It wouldn't happen again...would it? Well China has become the world's largest economy, built on industry and mass production. Sounds familiar. They are able to make a large amount of the world's consumable products, but that industrial drive is coming at a cost just like it did to London 70yrs ago. A combined World Bank and SEPA report estimated that 760,000 people died prematurely each year as a result of air pollution in China. China are in much tighter control of their media and what they report outside the country and specific incidents are not always reported. It seems that we as human beings are rather stupid. Fundamentally to survive our bodies require food, water and air. If we eat bad food, we get sick and can die. If we drink bad water, we get sick and can die. If we breathe bad air, we get sick and can die. It's not hard to figure it out, and yet time and again, we rely on prevailing winds to bring fresh air to blow away our own air pollution, and when the wind doesn't blow and we don't control our own air pollution...we die. It's pretty simple. So why do we keep screwing this up? If you're enjoying Causality and want to support the show you can like some of our backers: Eivind and Chris Stone. They and many others are Patrons of the show via Patreon and you can find it at Patrons can have a named thank you on the website, spoken at the end of the episodes, access to pages of raw show notes for every episode as well as an ad-free special release of every episode. There's a growing back catalog of re-edited episodes and a new making and episode tier if you're into that, so there's something for everyone, and if you'd like to contribute something, anything at all, it's all very much appreciated. Causality is part of The Engineered Network and you can find it and you can follow me on Mastodon @chidgey@ or for our shows on Twitter @Engineered_Net. This was Causality. I'm John Chidgey. Thanks for listening.
Duration 20 minutes and 3 seconds
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John Chidgey

John Chidgey

John is an Electrical, Instrumentation and Control Systems Engineer, software developer, podcaster, vocal actor and runs TechDistortion and the Engineered Network. John is a Chartered Professional Engineer in both Electrical Engineering and Information, Telecommunications and Electronics Engineering (ITEE) and a semi-regular conference speaker.

John has produced and appeared on many podcasts including Pragmatic and Causality and is available for hire for Vocal Acting or advertising. He has experience and interest in HMI Design, Alarm Management, Cyber-security and Root Cause Analysis.

You can find him on the Fediverse and on Twitter.