Meet the pigeons who are doing their bit for science, by helping to track how pollution moves around big cities.
We know that pollution from car engines rises up to rooftop levels, but these scientists want to find out exactly where it goes next.
It's a difficult thing to work out from the ground, so they've recruited some feathery friends to track what happens up in the sky.
They strap small sensors to the birds, so that they can record where they fly and how warm the air is.
Martin's been finding out how their first test flight went.