Wednesday, 22 October 2025

A Brief History of Air Pollution in the UK

(Image credit: Alan Frijns, Pixabay)

This will be a sharply cut down précis of some of my earlier work, which has documented the history of the science and politics of air pollution and anti-car policies in the UK.

Air Pollution Episodes

I shall first discuss some specific air pollution episodes, whose health effects have been proven to be serious and adverse. I shall concentrate mainly on two kinds of pollutant. First, sulphur oxides. And second, PM2.5 (that is, particulate matter small enough to find its way through the body’s defences into the lungs.) Though I shall also, towards the end, touch on the subject of nitrogen oxides.

The Great London Smog of 1952

During a cold, windless winter week-end in 1952, unusual amounts of air pollutants collected in the atmosphere in and around London. This produced a fog, in which visibility and air quality were both very poor for several days in a row. I wrote about this here: [[1]].

According to the government report the following year, this “smog” was accompanied by an immediate and sudden rise in both illness and mortality. Hospital figures show that respiratory disease nearly quadrupled, and heart disease levels were three times normal.

The blame was laid on a combination of sulphur oxides and “smoke” (what would now be called “particulate matter” or PM). The report said: “Both medical opinion and chemical investigation indicate that the deleterious effects of the oxides of sulphur are greatly enhanced by the presence of smoke particles.” This unhealthy combination was produced by the burning of low-quality coal, with a high sulphur content. As many as 12,000 people may have died from, or had their lives shortened by, the effects of the Great Smog.

The result was political action, and the Clean Air Act 1956, which led to a number of follow-ups. Over a decade and more, levels of air pollution, and particularly of sulphur dioxide, were significantly reduced.

Other smogs in London, the USA and Japan

Data from the time suggests that mortality from bronchitis in London rose by a factor of more than 10 between 1840 and the 1890s. This reflected a sustained increase in coal-burning, and in the “pea-souper” fogs, for which London became famous. Since then, a combination of regulation and technical improvements has reduced levels of both sulphur oxides and PM, which today are only 2 or 3 per cent of 1890s levels.

In the 20th century, there were similar smogs in other parts of the world. St. Louis in 1939 and New York City in 1966 were two major ones, and they resulted in political action. There have also been smog events, attributed to sulphur oxide pollution, in Japan. But I know of no such destructive smogs in the Western world since the early 1970s.

Before 1950, there had also been examples of serious health damage in Europe and the USA, due to fluorine compounds emitted into the air. However, there have been none since.

Hazes

Hazes are a more recent phenomenon, with similar effects to smogs. They have occurred since 1997 in south-east Asia and in China. There have also been smogs in China and India during that time.

All these seem to be associated with two sources of pollution. One, pollution from coal and other industry, like the Western smogs. And two, agricultural practices that burn vegetation on a large scale. Such practices often result in large seasonal emissions of PM and sulphur oxides together. Just like the known causes of the major Western and Japanese smogs.

Which pollutants are the toxic ones?

Looking at the field as an informed outsider, I see no evidence to contradict the conclusion of the UK government’s 1953 report on the Great Smog of London. Namely, that you need both PM and sulphur oxides together to produce a dangerous smog.

As to the toxins that directly cause the adverse health effects of this mixture, epidemiologist James Enstrom did a calculation a few years ago, which estimated the total PM ingested in a lifetime of breathing average US city air as about 5 grams. This means that, if these toxins are carried in the PM, they must be very toxic indeed when absorbed into the bloodstream. There are certainly three highly toxic divalent metals (cadmium, lead, and mercury) in PM, which might react inside the lungs to produce a sulphate that ends up in the bloodstream, and could cause the toxic metal to accumulate over the longer term.

Though there has been some science done in this area, notably in China, I am surprised that a problem which has been known about for 70 years seems to have been so little investigated.

The history up to 2008

I’ll look at the history chronologically, as I did earlier at [[2]].

The 1970s and 1980s

In the 1970s, the main focus in the scientific area of air pollution and health was monitoring.

Links between air pollution and health became in the 1980s more and more a political matter. And in Germany, the idea of ambitious “clean air” policies, requiring reductions of emissions from cars as well as from other emissions sources, was first mooted.

The Rio Summit and after

Then, in 1992, there was Rio. The agreements made there did not have a direct, immediate effect in the area of air pollution and health. But they surely inspired the UK government to start taking steps towards making air pollution into a hot-button political issue.

COMEAP, the Committee on Medical Effects of Air Pollution, was established in 1992. Professor Stephen Holgate, later to prove an activist in these matters, was its first chair.

Also in 1992, the EU (as it was soon to become) issued its first vehicle emissions standards. In the UK, catalytic converters were required in petrol engines. And the London Air Quality Network (LAQN) was formed, to monitor various pollutants.

In 1993, the Clean Air Act regulated the content of motor fuels. And in the USA, the “Six Cities” study was published, which became the baseline for assessing health effects of PM.

The UK Environment Act 1995 brought a requirement for government to prepare a National Air Quality Strategy. In 1996, the EU issued its Ambient Air Quality Directive. And 1997 brought the publication of the first UK National Air Quality Strategy. All the time, the UN’s World Health Organization (WHO) was working behind the scenes, setting “guidelines” for concentrations of many pollutants, and bedding-in the culture of ever-tightening, collective limits, to which we have been increasingly subjected ever since.

In 1998, the EU issued a new directive on fuel standards. And COMEAP addressed for the first time the issue of links between air pollution and health. In 1999, the UK signed up to the Gothenburg Protocol. And from 2000 on, the scope and pace of regulation only increased. The 2001 EU National Emissions Ceiling directive was a significant marker on the trail that led to air pollution being used more and more as an excuse to violate our rights and freedoms.

In 2003, work started towards the London Low Emissions Zone (LEZ). In 2005, the EU’s “Clean Air for Europe” program began. Also in 2005, the WHO updated its air quality guidelines, including a guideline for PM2.5 an order of magnitude lower than previous limits, even the EU’s.

One intervention in 2006, which did seem to produce positive results, was stricter controls over the sulphur content of marine fuels. And in 2007, the introduction of ultra-low sulphur diesel does seem to have had positive effects in reducing the amount of very small PM, as well as sulphur oxides; not surprising, given what we know from the Great Smog! What is surprising, though, is that – almost uniquely, it seems – this was achieved at reasonable cost.

In 2008, the EU issued yet another omnibus directive, on Ambient Air Quality and Cleaner Air for Europe. And the London LEZ went into operation.

The COMEAP report of 2009

2009 marks a watershed over this issue. For in that year, COMEAP produced a report which, apparently, laid a “scientific” foundation that enabled government and activist campaigners to make out that air pollution was a more serious problem than had previously been thought.

One thing I found strange was that COMEAP focused only on the level of PM2.5 in order to estimate the risk, irrespective of what that PM contained, or what other pollutants it was accompanied by. The idea that “all PM2.5 is equal” in toxicity does not seem to me to be anywhere near proven, even though this is the official line maintained by the WHO. Indeed, as above, historical evidence strongly suggests that PM2.5 and sulphur oxides together are more toxic than either of them alone.

You can read the full essay at [[3]]. Here are some of my conclusions from the end of that essay.

That the focus was on effects of pollution reductions, rather than on gauging the scale of the pollution problem as a whole, worried me from the start. The “expert elicitation” exercise to determine confidence intervals gave me no confidence at all. That the direction of the report, and what it would study, had been set as early as the beginning of 2006, got me concerned about the integrity of the scientific process which led to its results. And that the whole exercise ended up slavishly following the WHO’s recommendations – even in the confidence intervals! – raised a red flag for me.

That the report concentrated on long-term exposure, when historical evidence suggests that the biggest proven negative health effects from air pollution have come from episodic exposures, struck me as obtuse. Moreover, the significant role of sulphur compounds in combination with PM in causing health damage was not properly addressed, even when brought up by two of the peer reviewers. This damaged further my confidence in the integrity of the processes. And the presence on the committee of at least one activist on the issue did not inspire me with confidence in its impartiality.

All of these pieces of evidence combined to lead me to my conclusion. This report was not an honest attempt to inform policy assessments by quantifying the risks arising from PM2.5 pollution in the UK. It was far more like an exercise in creating “evidence” to suit previously determined policies. It was simply an excuse – a 180+ page excuse – for falling into line behind the WHO’s position on the matter. It was not science, but politics.

The history from 2009 onwards

The three essays which tell the back-story in detail from 2009 are here: [[4]], [[5]], [[6]]. It is a long and tangled tale, and I shall select only a few of the events most important from the air pollution toxicology point of view.

2009 to 2013

In 2009, the LAQN (London Air Quality Network) report for 2006/7 identified that the EU limit value for nitrogen oxides was being exceeded in many places in London. Curiously, the 2008, 2009 and 2010 reports weren’t published until 2012!

The major UK report of 2010 in the air pollution area was the follow-up to the COMEAP report of 2009. It concluded: “An effect on mortality in 2008 of nearly 29,000 deaths in the UK at typical ages and an associated loss of total population life of 340,000 life-years.” Figures like these are still bandied about today by those of an activist bent.

In 2011, a UK team reviewed how much effect the LEZ charging scheme had had on air pollution levels since 2003. The answer to the question was, in brief, not very much.

By 2012, the culture of arbitrary, ever tightening, collective “targets” and “limits,” that had been conceived by the EU, adopted by the UN, and supported by politicians that ought to have known better, was in full swing. And in Europe, the EU had become its policeman. In the same year, some of the saner UK air quality experts issued a report that “challenges the robustness of the evidence for making future policy decisions in respect of PM2.5 in the UK context.” But they were not listened to.

The main air pollution story of 2013 came from the WHO and the EU. In that year, they started promoting air pollution as a really big problem, with a project called REVIHAAP. (“Review of Evidence on Health Aspects of Air Pollution.”) A sister project, HRAPIE, “Health Risks from Air Pollution in Europe,” summarized the views of “expert stakeholders.”

I cannot avoid thinking that the WHO and EU must have funded these two projects in order to bias air pollution science towards activism.

2014 to 2018

In 2014, the European Commission, the executive of the EU, took the UK to court for exceeding nitrogen oxides limits. And in 2015, DEFRA (Department for Environment, Food and Rural Affairs) issued a report on nitrogen oxide pollution, which made out that these gases had worse effects than previously thought.

The major event of 2016 in the air pollution field was a report by the RCP (Royal College of Physicians) and the RCPCH (Royal College of Paediatrics and Child Health). It was titled “Every breath we take: the lifelong impact of air pollution,” and was alarmist and activist. Its figure of 40,000 deaths each year due to PM2.5 and nitrogen oxides went viral in the media. The chair of the working group that produced this report was Professor Stephen Holgate.

In 2017, the UK government issued a Draft UK Air Quality Plan for “tackling” nitrogen dioxide. This laid the foundation for Clean Air Zones, charging entry fees for non-compliant cars and vans. Moreover, it explicitly planned the upcoming London Ultra Low Emissions Zone (ULEZ), from the “T-charge” of 2017, via the launch of ULEZ in 2019, to its extension to the North and South Circular Roads that was to happen in 2021.

In 2018, COMEAP issued another report, on “Associations of long-term average concentrations of nitrogen dioxide with mortality.” It shows evidence of a rather confused genesis, for example: “Policy needs have determined the focus on NO2 in this report.”

On this occasion, the committee could not reach agreement on its conclusions. Three brave dissenters said, rightly in my view: “there is insufficient evidence to infer a causal association between long-term average ambient NO2 concentrations and risk of death.” But the majority pressed on regardless, saying: “There is a case for an NO2 contribution of unknown size.” And, despite admitting that they did not know its size, they gave a risk figure for it anyway!

Another, landmark event of 2018 was a real-world study by Professor Chris Griffiths, which investigated the impact of London’s LEZ on air quality and children’s respiratory health. It “found no evidence of a reduction in the proportion of children with small lungs over this period, despite small improvements in air quality in highly polluted urban areas during the implementation of London's LEZ.” But Shirley Rodriguez, deputy mayor of London, did not like this outcome, and pressured Professor Griffiths to change his conclusions. Which he, to his credit, refused to do.

2019 to the present

I do not think that I need to give much detail on all that has happened since 2019; you can use your own memories, or refer to my original essays. A few bullet-points should suffice.

·       The COVID panic, and all that went with it.

·       The “consultation” on “de-carbonizing transport.”

·       The “Great Reset.”

·       A labelling change, instituting a “Clean Air Programme” and a “Clean Air Day.”

·       New, and greatly tightened, air quality guidelines from the WHO.

·       Extension of ULEZ to the North and South Circular Roads.

·       The first “Clean Air Zones.”

·       An Imperial College study that concluded, “The ULEZ caused only small improvements in air quality in the context of a longer-term downward trend in London’s air pollution levels.” Which, again, the Deputy Mayor of London tried to suppress, this time with help from the then chair of COMEAP.

·       Announcement of “Clean Air Champions,” including Professor Stephen Holgate.

·       A most revealing 2022 “Chemical Hazards and Poisons Report” from the UK Health Security Agency.

·       Extension of ULEZ to Outer London, and the judicial shenanigans that went with it.

·       Activist, anti-car local transport plans springing up, even in rural counties.

·       The WHO’s overblown and unachievable “Vision Zero” road safety scheme.

·       And much more…

To sum up

In this missive, dear reader, I have given you many individual snippets of information. They are like dots in a pattern. Can you connect the dots, and work out what has actually been going on in the world of air pollution toxicology since the 1980s or thereabouts?

To give you a little hint: We’ve been had, haven’t we?

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