Air Pollution Warning London
In short
London is currently under a high air pollution alert because dense fog and light winds have trapped smoke from bonfires and fireworks near the ground. PM2.5 levels have reached five times the World Health Organization guidelines despite a seemingly moderate Air Quality Index.
In plain words
Thick fog is preventing smoke and pollutants from blowing away, causing them to build up over the city. This makes the air unhealthy to breathe, especially for vulnerable people. Mayor Sadiq Khan has advised residents to limit their time outdoors.
A simple example
A person walking through a foggy street might breathe in tiny particles from recent fireworks that cannot escape the low-lying mist.
Why it matters
High levels of PM2.5 particles can enter the lungs and bloodstream, causing health issues. The current weather conditions make it difficult for the city's air to clear naturally.
Easy to mix up
Do not confuse this pollution alert with a standard smog warning; this specific event is driven by seasonal bonfire smoke trapped by weather.