Last year, Breathe London created a network of 100 state-of-the-art sensors and began driving two specially equipped Google Street View cars through the capital to measure air pollution. While researchers will continue to gather and analyse millions of measurements over the course of 2019, we can begin to share snapshots of the data coming in.

The graphic below shows data from a single Google Street View car driving in Southwark and Lambeth on an afternoon last September. The map also shows the location of nearby Breathe London fixed monitors in purple and the city’s existing air pollution monitors, known as the London Air Quality Network in blue.

As the car drove between Vauxhall, Oval, Kennington and Elephant & Castle, it measured nitrogen dioxide (NO₂) pollution, picking up areas of higher concentration seen on the below map. It also collected data on particulate matter (PM₂.₅), ozone, ultrafine particles and carbon dioxide (CO₂), which are shown in the graphs on the left.

Graphic 1 – Data represents 1 to 5 second measurements in micrograms per cubic meter (μg/m3).

Although our findings are not directly comparable to World Health Organisation (WHO) guidelines, which are based on annual average, hourly or daily average exposures, we share them here for reference.

Red dots on the above map indicate air pollution levels above the guidelines for short-term exposure set by the WHO. Orange dots indicate levels that are lower than the hourly or daily average exposure guideline but higher than the annual guideline. Yellow dots indicate levels below WHO guidelines.

To get a more complete picture of a street’s long-term air quality and how it compares with WHO guidelines, the cars will capture data in the same location multiple times, at different times of the day, week and year to account for everything from holiday traffic patterns to changes in weather.

Stationary pods offer 24/7 monitoring

Fixed Breathe London monitors have also been installed at three primary schools in the area.

The graphs below show how nitrogen dioxide and particulate matter varied at the schools between 11th December and 3rd January and compares these findings to WHO guidelines.

NO2 & PM levels at three primary schools

At all three schools, the concentrations of NO₂ and particulate matter (PM₁₀ and PM₂.₅) were elevated on 27th and 28th December. Particulate matter was also noticeably higher between 11th and 15th December. Although NO₂ doesn’t exceed average hourly WHO guidelines, the average daily limit for PM₁₀ is exceeded at one school and for PM₂.₅ at two schools on more than one day. In particular, PM₂.₅ levels – which can have health impacts at very low concentrations – remained above the average daily limit for a number of days at one of the schools. At all three sites, levels of particulate pollution exceeded the WHO annual thresholds on a number of days.

While this data represents just a few weeks, if these trends continue, the schools will show annual levels of particulate pollution at levels the WHO has deemed unsafe.

Coming soon: interactive maps and modelling

The Breathe London project will continue collecting data across Greater London every day for most of 2019. Coupled with sophisticated modelling, we will identify previously unknown pollution hotspots – locations exhibiting persistently high pollution levels.

This ability to look at several pollutants at once will provide us with increasingly detailed and robust pictures of air quality, helping us identify and understand sources of pollution. This knowledge in turn can be used to design solutions in the areas that need them most.

Breathe London looks forward to sharing data and analysis over time. To receive these, you can sign up for updates by email in the box below.

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