AHAH (the index of 'Access to Healthy Assets and Hazards') is a multi-dimensional index developed by the Geographic Data Service for Great Britain measuring how 'healthy' neighbourhoods are based on accessibility to health-promoting and health-damaging features of the built environment. The AHAH index combines indicators under four different domains:
- Retail environment (access to fast food outlets, pubs/bars, tobacconists, gambling outlets),
- Health services (access to GP surgeries, hospitals, pharmacies, dentists, leisure centres),
- Physical environment (Blue Space, Active Greenspace, Passive Greenspace via NDVI), and
- Air quality (NO₂, PM₁₀, SO₂).
The dataset available for download contains each input component used to generate the AHAH Index. For accessibility indicators (e.g. GP, dentist, fast_food), values represent the mean drive-time in minutes from postcode centroids within each LSOA/Data Zone to the nearest point of interest. For greenspace (passive), the value represents the median NDVI (Normalised Difference Vegetation Index) derived from Sentinel-2 satellite imagery. Air quality components indicate the area-weighted mean concentration of pollutants (µg/m³).
For each component, the rank (_rnk) and percentiles (_pct) are normalised so that lower values indicate healthier environments in terms of expected impact on health, while higher values indicate less healthy environments. The composite AHAH score follows the same convention: higher scores = less healthy neighbourhoods.
Content
Measurement data, ranks and percentiles for the overall index, 4 domains and 15 input indicators are produced for Lower Layer Super Output Areas (2021 LSOAs) for England and Wales, and Data Zones (2022 DZs) for Scotland, comprising 43,064 small areas across Great Britain.
Accessibility measures are calculated as the mean travel time (in minutes) by car along the road network, from each postcode centroid within the statistical area to the nearest point of interest. Travel times are calculated using the Valhalla open-source routing engine with OpenStreetMap road network data, assuming free-flow traffic conditions.
Please see the Technical Methodology Report for comprehensive documentation of the data sources and index construction methodology.
For detailed description of all columns contained within the data, see the Variable Dictionary; and for an overview of the characteristics of the data, see the Data Summary. These files can be downloaded from the bottom of this page.
Quality, Representation and Bias
The data are compiled from multiple authoritative sources selected for quality and coverage. Health service locations are derived from official NHS administrative datasets. Air quality data uses DEFRA's validated modelled surfaces. Greenspace metrics are derived from European Space Agency Sentinel-2 satellite imagery processed via Google Earth Engine.
Accessibility calculations achieve near-complete coverage, with fewer than 0.02% of postcodes returning missing routes (primarily in remote island locations). At the LSOA/Data Zone level, no areas have complete missing values for any indicator.
Users should note that:
- Travel times assume private vehicle access with free-flow traffic conditions
- Retail environment data is subject to commercial classification schemes
- Temporal alignment varies across indicators (health services: late 2025; air quality: 2024; greenspace imagery: April-September 2024)
Version History
Version 5 was released in February 2026 and is the current release. It it is the first release to use the 2022 Scottish Data Zone census boundaries. It re-added an Active Greenspace indicator and used the Valhalla routing engine. Version 4 was released in late 2024 and used 2021 England/Wales LSOA census boundaries and 2011 Scottish Data Zone census boundaries. Version 3 was released in late 2022 and (like Version 2 and 1) used the 2011 LSOA/DZ census boundaries. Version 2 was released in 2017 and revised the methodology from the original Version 1 (2016) release.
Previous versions are available from the "Previous versions" record linked below.
