Story · Environment map · about 3 min
The air we breathe: 14 years of cleaner London
Defra models the background air pollution of every 1 km square in the UK each year. Here is what changed between 2010 and 2024, and what has not.
Nitrogen dioxide, 2010
In 2010 the typical 1 km square in the UK had 8.0 µg/m³ of background nitrogen dioxide, but central London had 62.2. The WHO's 2021 guideline for the annual mean is 10, and 33% of UK squares were above it. NO2 mostly comes straight out of vehicle exhausts and irritates the lungs, which is why the map tracks roads so closely. Notice the motorways drawn as lines.
Nitrogen dioxide, 2024
By 2024 the UK average was 3.4 µg/m³ and central London 33.1. Only 3% of squares were above the WHO guideline. These are background levels, so roadside air is worse than this map shows. Defra refines its model every year, so read the broad direction rather than any one year’s wobble.
Fine particles are the harder problem
PM2.5 is fine enough to reach deep into the lungs and bloodstream, and it does not stay near its source the way NO2 does. It drifts in from wood burning, farming and other countries as well as traffic, so it rarely falls neatly along roads. The WHO guideline is 5 µg/m³. In 2010 97% of UK squares were above it; in 2024 it was still 41%, with London at 10.5.
For classrooms and curious minds
Questions to talk about, alone or in a group.
- Which sources of pollution would you expect to fall fastest, and which to be hardest to cut?
- Why is a background level different from what you breathe at a busy roadside?
Try it on the map: Compare nitrogen dioxide in 2010 and 2024 around a city you know. Where did it fall most?
The figures above are calculated from the datasets listed on Data & sources and are approximate: many map layers are modelled or interpolated. Read each layer’s caveats on the map.