How we measure the environment
Three separate measures: the air you breathe, the chance of flooding, and how much green space is nearby. Only air quality is turned into a score.
- Sources
- Defra, Environment Agency, Ordnance Survey
- Flood data updated
- Quarterly
- Air quality measured for
- 1 km grid square
- Green space measured for
- 2 km around the postcode
- Air quality scale
- 10–100, higher is cleaner
Air quality
Find the grid square
Defra models annual background pollution concentrations across every 1 km square of the UK (Pollution Climate Mapping). We identify the square containing the postcode and retrieve the latest reference year data.
Read four modelled pollutants
Annual mean concentrations of nitrogen dioxide (NO₂), fine particulate matter (PM2.5), coarser particulate matter (PM10), and sulphur dioxide (SO₂).
Evaluate against UK limits, 2040 targets & WHO guidelines
Each pollutant is benchmarked against statutory UK annual limits, the UK Environmental Targets 2040 PM2.5 objective (10 µg/m³), and the World Health Organization (WHO 2021) health guidelines.
Rank nationally on the EEA scale
Concentrations are classified on the European Environment Agency (EEA) Air Quality Index band, and ranked nationally to compute the share of UK areas with worse air quality (a score from 10 to 100, where 100 is the cleanest decile).
- 10
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- 30
- 40
- 50
- 60
- 70
- 80
- 90
- 100
Air quality is reported with reference to its European Environment Agency (EEA) band and compared against UK legal limits, the statutory 2040 PM2.5 target, and World Health Organization (WHO 2021) guidelines. Percentile ratings report the share of UK areas with worse air quality.
| Pollutant | UK legal limit | 2040 UK target | WHO (2021) guideline | Context |
|---|---|---|---|---|
| Nitrogen dioxide (NO₂) | 40 µg/m³ | — | 10 µg/m³ | Combustion and traffic emissions |
| Fine particles (PM2.5) | 20 µg/m³ | 10 µg/m³ | 5 µg/m³ | Statutory 2040 UK target (Env. Targets Regs 2023) |
| Coarse particles (PM10) | 40 µg/m³ | — | 15 µg/m³ | Dust, construction, brake and tyre wear |
| Sulphur dioxide (SO₂) | 20 µg/m³ | — | — | UK/EU annual limit for vegetation and ecosystems |
Flood risk
The Environment Agency grades the long-term chance of flooding from rivers and the sea for every property in England. We show the highest band that applies to any property in the postcode, along with how many properties fall in each band.
| Band | Chance of flooding |
|---|---|
| High | More than 1 in 30 (3.3%) each year |
| Medium | Between 1 in 100 (1%) and 1 in 30 (3.3%) each year |
| Low | Between 1 in 1,000 (0.1%) and 1 in 100 (1%) each year |
| Very low | Less than 1 in 1,000 (0.1%) each year |
The Environment Agency only lists postcodes with property in an area at risk, so a postcode that isn’t listed is shown as very low. Flood alerts and warnings in force right now are checked live when the report loads.
Green space and trees
We draw a 2 km circle around the postcode and find the parks, playing fields, allotments and other public green spaces from Ordnance Survey, plus woodland from the National Forest Inventory, whose centre falls inside it. The report shows what share of the circle they cover, and the share that is woodland, capped at 100%.
What it can’t tell you
- Air quality is a modelled background level for the whole square. It will be higher beside a busy road and lower on a quiet street.
- The pollution maps are annual averages, so they don’t show short spikes or today’s conditions.
- Flood bands cover rivers and the sea only. They don’t include flooding from heavy rain (surface water) or groundwater, and they don’t reflect defences or flood protection on an individual property.
- Flood bands cover England only.
- A large park counts in full if its centre is within 2 km, even if much of it lies outside the circle, which can overstate green space near big parks.
- Green space and woodland data covers Great Britain only, so Northern Ireland postcodes show none.