Environment Methodology
We measure environmental factors including air quality, flood risk, green space, and environmental deprivation using UK government datasets.
Data Sources
- DEFRA Air Quality — Daily Air Quality Index (DAQI) by monitoring stations and modeled grid
- Environment Agency Flood Risk — Flood zones and historical flood events by postcode
- Environmental Deprivation Index (IMD) — Index of Multiple Deprivation environmental domain
- OS Open Greenspace — Parks, public gardens, playing fields and other public green space
- National Forest Inventory — Woodland cover from the Forestry Commission
- ONS Access to Gardens & Public Green Space — Park and private garden access by LSOA
- Update Frequency — Air quality updated daily; flood data updated annually; IMD every 2–4 years
Air Quality (DAQI)
We report the Daily Air Quality Index (DAQI), a 1–10 scale used by DEFRA:
| DAQI | Level | Health Advice |
|---|---|---|
| 1–3 | Low | Air quality is satisfactory |
| 4–6 | Moderate | Members of sensitive groups may experience health effects |
| 7–8 | High | Members of sensitive groups should consider limiting outdoor exposure |
| 9–10 | Very High | Health warnings; avoid outdoor activity |
Flood Risk Zones
The Environment Agency classifies flood risk into three zones:
- Zone 1 (Low) — <0.1% annual probability of flooding
- Zone 2 (Medium) — 0.1–1% annual probability
- Zone 3 (High) — >1% annual probability; may benefit from flood defenses
Environmental Deprivation Index
The IMD includes an Environmental Deprivation domain covering air quality, road traffic accidents, proximity to waste dumps, and proximity to noisy facilities. We report this as a percentile rank (0–10 scale) where 10 is least deprived environmentally.
Green Space & Tree Canopy
Green space figures count OS Open Greenspace sites and National Forest Inventory woodland whose centre lies within 2km of the postcode. Percentages are the share of that 2km circle covered by those sites, and tree cover counts the woodland portion only. Garden access and distance-to-park figures come from the ONS release for the postcode's LSOA.
Limitations
- Air Quality Modeled — DAQI is often interpolated from monitoring stations; many postcodes lack direct measurement
- Flood Risk Historical — Data reflects past events and current defenses; extreme weather patterns may change risk
- Green Space Approximate — Sites are counted from their centre point, so a large park straddling the boundary counts in full; woodland below 0.5 hectares is not in the National Forest Inventory
- No Noise Data — We don't currently report noise levels; only IMD environmental deprivation
- Climate Change Not Modeled — Flood risk reflects historical patterns, not future climate scenarios
Data Attribution
Contains data from DEFRA and Environment Agency, licensed under the Open Government Licence v3.0.
Contains OS data © Crown Copyright and database rights.
Contains, or is based on, information supplied by the Forestry Commission.