Donald Acheson knows London like the back of his hand. But in December 1952, while working in a bustling downtown hospital, a routine assignment turns into a disorienting and dangerous disaster.

An ominous fog has overtaken the city, enveloping it in a thick layer of black air and soot. Lost in the streets he knew so well, the young doctor had to “crawl along the pavement along the wall of the building, to the next corner, to read the name of the street.” He walked back to the hospital amidst what was to come remember as a “terrifying silence”.

The phenomenon is also called smog (smoke mix, smoke, and fog, fog, in English) has found its way into the hospital where Acheson works, and into the lungs of his ER patients. Soon the hospital reached a critical juncture, its morgue filled with patients who died from respiratory and heart problems.

(Related: What is air pollution? here are the basics).

The terrible, suffocating fog has earned its nickname: The Great Mist (or Big Smoke). Between 5 and 9 December 1952, this environmental disaster engulfed London. It will affect Britain’s health (and its climate) for years to come. Here’s how the fog affected the chilly city and how it continues to affect Britain today.

consumed by coal

London has struggled with air quality for a long time, ever since that “Great Smell.” radiated from the polluted sewage of the Thames in the 1850s to the epic”pea soup” [sopas de guisantes] the city, a long time ago when exhaust from factories and heating stoves hung a green haze over the streets. In 1905, the physician Harold Antoine des Voeux coined the term smogto describe the atmosphere of the city.