When you hear the words "pea soup", you probably think of, well, pea soup. But pea soup is also the name of a particular type of thick fog, and in the early 20th century London was literally drowning in it.

Also known as black fog or killer fog, it's caused by soot particles and poisonous sulfur dioxide produced by the burning of soft coal in homes and factories. The fog is potentially lethal, especially for the elderly and those with respiratory problems, and as you can see from these vintage photographs, there was no way to escape it. The choking pollution culminated in the Great Smog of 1952, and although the Clean Air Act was implemented just four years later, an estimated 12,000 people are believed to have died as a result of the hazardous air pollution. (h/t: vintage everyday)

#1 A Lamp Lighter At Work In Finsbury Park, London, 17 October 1935

A Lamp Lighter At Work In Finsbury Park, London, 17 October 1935

Topical Press Agency Report

Danielle Goedhart 2 years ago

Absolutely love this picture! ❤️

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#2 A Man Lighting His Pipe In Thick Fog Under The Arches At The Temple, London , 23 December 1935

A Man Lighting His Pipe In Thick Fog Under The Arches At The Temple, London , 23 December 1935

Arthur Tanner Report

Cathy Lowery 2 years ago

Like a scene straight out of a mystery movie!

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#3 Fleet Street, 6 December 1952

Fleet Street, 6 December 1952

Edward Miller Report

Sarai Morrissette 2 years ago

Look like a charcoal drawing.

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#4 Lincoln’s Inn Fields, 24 January 1934

Lincoln’s Inn Fields, 24 January 1934

Fox Photos Report

Tulip 2 years ago

Mr. Holmes in London :)

#5 Central London, January 1936

Central London, January 1936

Lacey Report

Kushal Ghosh 2 years ago

The poster " WANTED FOR MURDER " :O

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#6 Westminster Bridge, 14 January 1955

Westminster Bridge, 14 January 1955

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#7 National Gallery, Trafalgar Square, 1 December 1948

National Gallery, Trafalgar Square, 1 December 1948

Warburton Report

Helga Novelli 2 years ago

They knew how to decorate the Christmas tree in Trafalgar Square at that time!

#8 The Tower Of London, January 1947

The Tower Of London, January 1947

Fox Photos Report

#9 An Iceman Delivers In The Fog, 1 October 1919

An Iceman Delivers In The Fog, 1 October 1919

Topical Press Agency Report

Eeva Kulmala 1 year ago

The clear ice is a stunning contrast to the opaque fog.

#10 Liverpool St. Station, 29 January 1959

Liverpool St. Station, 29 January 1959

Edward Miller Report