Great Smog of London

Throughout the 19th century, dense fogs in London, known as “pea‑soupers,” became increasingly prominent and deadly due to industrial coal emissions. These yellowish, opaque smogs impaired vision, disrupted transport, and caused fatal respiratory issues, yet they were largely tolerated due to industrial growth and domestic heating needs.

In 1968, legislation was introduced to strengthen the Clean Air Act, particularly addressing industrial emissions. It mandated taller chimneys for factories burning coal, gas or other fuels, and further restricted smoke from industrial sources to improve air quality and public health.

From December 4 to 7, 1962, London experienced another severe smog event that, while less toxic than in 1952, still caused up to 700 deaths and widespread disruptions. This demonstrated lingering shortcomings in the 1956 Clean Air Act and prompted further revisions.

On July 5, 1956, the UK Parliament passed the Clean Air Act as direct response to the Great Smog. The legislation created “smoke‑free zones,” restricted coal burning in urban areas, and funded grants for households to switch to cleaner heating sources. It marked a pivotal shift in environmental policy.

By the end of 1953, atmospheric scientist E. T. Wilkins and other researchers had identified elevated death rates through March of that year, suggesting approximately 12,000 excess deaths linked to the smog — three times the initial estimate. These delayed fatalities underscored smog’s prolonged health effects.

In early 1953, the Registrar General published figures attributing about 4,000 deaths directly to the Great Smog, mostly from pneumonia and bronchitis. This initial official toll, while alarming, would later be revised upward as indirect fatalities were accounted for.

On December 9, 1952, a shift in weather brought wind that dispersed the lethal smog blanketing London. Although visibility cleared, the human toll had been immense, and the true impact would only be understood in the weeks and months to follow through mortality data and public health observations.

By December 6, the smog thickened to a pea‑souper of unprecedented density. Visibility dropped to mere metres; surface transport stalled, ambulances and cars were stranded, events were cancelled, and crime rose as thieves vanished into the haze. Indoors, the smog penetrated theatres and public spaces, adding to chaos.

On December 5, 1952, a dense, yellow‑brown smog began to envelop London. A severe temperature inversion trapped smoke from domestic coal fires, factories, and vehicles, preventing dispersion. The smog rapidly reduced visibility, halted surface transport, and seeped indoors — marking the onset of Britain’s worst air pollution disaster.

In 1661, diarist John Evelyn published Fumifugium, one of the earliest documented concerns about air quality in London. He described the “inconvenience of the aer and smoak of London,” highlighting early recognition of pollution caused by coal burning. While smog was once a natural fog, by Evelyn’s time it was already laden with smoke — an early stir in environmental awareness.