Many of us don't give much thought to the air that we breathe, but scientists from the University of Leicester are doing just that to learn how pollution affects us.
In a world-first experiment they've mapped the whole of the city by plane, to see how fumes and emissions are carried around. They hope the work will mean we can lead cleaner, healthier lives. Chris Halpin reports.
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A large tent has been put up around the area while investigations continue.