# Bad air, but bad with what

> The headline index hides which pollutant is doing the damage.

- Category: Environment
- Cadence: live
- Status: Live: values change continuously; cite the retrieval time.
- Dataset key: `live-pollutants`
- Source: [Environment Agency](https://www.londonair.org.uk/)
- Licence: Open Government Licence v3.0 — [terms](https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/)
- Canonical page: [https://londongraph.com/g/bad-with-what](https://londongraph.com/g/bad-with-what)
- Machine-readable record: [https://londongraph.com/data/bad-with-what](https://londongraph.com/data/bad-with-what)

## Methodology

Median Daily Air Quality Index across every reporting LondonAir site, held separately per pollutant. The single headline figure is each site's worst pollutant, which answers whether the air is bad and hides what it is bad with. Nitrogen dioxide is largely a traffic story and PM2.5 largely a weather one; they neither peak together nor in the same places.

## Visualisations

- [Overview](https://londongraph.com/g/bad-with-what): The headline index hides which pollutant is doing the damage.
- [Pollutants](https://londongraph.com/g/bad-with-what?view=pollutants): Compare median DAQI and reporting-site coverage by pollutant.

## Citation guidance

Attribute the original publisher named above and identify LondonGraph as the visualisation and methodology layer. Do not describe live values as a historical census, and do not present placeholder values as observations.