Leicester has become the first city in the world to have its air quality mapped out using an airborne pollution-scanning device.
This bird's eye image shows how concentrations of potentially harmful nitrogen dioxide (NO2) – which increase the risk of respiratory illnesses – vary across the city.
It was taken by researchers from the University of Leicester from a survey plane flying 900m above the city's roads, parks, industrial estates and houses.
Physicists from the university's Earth Observation Science group, based in its Space Research Centre, took pictures using a ground-breaking "spectrometer" device mounted on the underside of the aircraft.
Project leader Dr Roland Leigh said: "This is the first time in the UK anyone has been able to use airborne devices to map pollution levels. It is also the first time a whole city has been mapped out in this way anywhere in the world."
The device measures visible light, and because NO2 absorbs sunlight, it shows how much is lost at different wavelengths.
They collated all the readings and overlaid the results over Google Earth maps – giving a detailed map of air quality in the city and surrounding areas.
Particularly clean areas of the city – indicated by the darker blue spots on the map – include Knighton Park, Oadby Race Course and Western Park Golf Club.
More polluted areas – shown in yellow – include Leicester train station, St Nicholas Circle roundabout, and junction 21 of the M1.
Dr Leigh said: "Other maps of this nature are constructed using various recorded data, whereas this is pretty much a real time image taken as we flew over Leicester.
"One of the most interesting things we discovered is just how quickly air quality improves.
"For example, just north of the A47 to the west of our scanned area is Western Park, which despite being right next to a very busy road has a lot of clean air. That surprised us."
This research was carried out as part of the UK's airborne air quality mapper project.
The university team has also been working with the city council, using its research to help develop traffic management schemes and reduce vehicle emissions.
Dr Leigh said: "This information helps us understand the sources of pollution. The results could help draw attention to polluted areas and inform environmental planning decisions."
The researchers hope to carry out further flights with industrial partners Bluesky International Ltd, specialists in aerial imaging and remote sensing data collection and processing.
In time, the plan is to adapt the technology to use on spacecraft in order to monitor pollution levels across the whole planet.
