City-scale air pollution measured for the first time

Seated on the University of Leicester’s Space Research Centre rooftop, the novel instrument captures the sun’s rays and uses them to build up a daily picture, in 3-D, of the city’s air pollution. Just the size of a suitcase, the instrument has nine telescopes that protrude out and point in different directions across the city, collecting the sunlight every minute of every day. The trapped sunlight is bounced by mirrors inside the instrument straight into the mouth of a device that measures its properties. These are then used to work out how much light has been absorbed by air pollutants before reaching the instrument.

Crucially for Leicester, the instrument can measure levels of nitrogen-dioxide in the air, a pollutant produced by traffic and one which poses a particular problem for the air quality in the city centre.

Dr Paul Monks, lead scientist on this project said, “90% of the nitrogen dioxide problem in Leicester is attributable to road traffic. Because our instrument looks at the whole city, it can identify when and where the pollution hotspots will occur during a typical day.” He added, “The level of detail we have seen is remarkable. For example, one Saturday we could pin-point the cause of air pollution to a football match, owing to the increased volume of traffic. On hot, sunny days when the air is still, such pollution could pose real health problems to residents”.

This technology will be of particular use to all local authorities in the UK who are currently required to review and assess local air quality to ensure objectives for key pollutants are being met. Its development is particularly timely given the predictions for more UK summer heatwaves with future climate change, and their potentially deleterious effect on air quality in urban areas.

“We will certainly be making this instrument available to Leicester City Council to help it design its current air quality action plan” said Dr Paul Monks.

In addition, the instrument has proven such a success and is so compact that the scientists plan to mount it on a satellite next year, where it can keep an eye on global pollution too.

This research forms part of the UK’s Atmospheric Science Strategy, which is supported by NCAS – the Natural Environment Research Council Centres for Atmospheric Science.