London Air


Air quality is an enormous problem across the globe, and particularly in large cities like London. To aid reporting on the issue, London Air provides an interactive portal to monitor and collect relevant data.

The data

Air pollution data is collected from monitors in each of London's boroughs, and supplemented with measurements from local authorities surrounding London in Essex, Kent and Surrey. The data dates back to 1993, and includes indicators for Carbon Monoxide, Nitrogen Dioxide, Ozone, PM10 Particulates, PM2.5  Particulates, Sulphur Dioxide, and a combined measurement.

To explore the data, London Air offers an interactive, map-based interface that can be queried based on monitoring site and postcode, or manually on the map, as well as by date and time. It also allows you to compare levels against World Health Organisation guidelines, and drill in on particular pollution episodes.

Image: A comparison of Westminster's pollution levels with the World Health Organisation's guidelines.

For breaking data, there is a live feature called Nowcast, which shows current air pollution in detail across London with reference to the UK Government's Daily Air Quality Index. By zooming into the map, it's possible to discover areas with higher or lower pollution levels at the current point in time, such as those areas close to busy roads during peak time. 

Image: Nowcast.

To power the map, data is created by combining readings taken within the last hour and air pollution modelling. This is done by merging together the four pollutant indicators, taking the highest of the air pollution index at each location. However, the accuracy of Nowcast varies for each hour, so it's important to check its performance rating before relying on its data. 

Image: Nowcast's performance rating at 06:00 on Monday, 5 February 2018.

London Air's data is also available via API.


The resource offers a number of simple tools to assist in reporting on its data. For example, there is a Widget Builder to easily build an interactive visual, which can be embedded in stories.

Image: A Widget created using London Air's builder.

In addition, there is a graphing function and statistics reporting tools

Image: London Air's graph tool.

Example use

Using London Air data, the Guardian developed an interactive map that tracks breaches of legal limits. The map allows you to compare breaches in 2018 with 2017 and, just one month into the year, revealed that London had reached its legal limit for nitrogen dioxide.

Image: The Guardian.

Complementing this map, the Guardian also put together a suite of graphs that breakdown the month's data by pollution site.

Image: The Guardian.

Explore London Air here.