CrowdScience dives back into a debate about trees and their ability to tackle air pollution. Growing trees take in carbon dioxide and emit oxygen, but their leaves also attract tiny particles, which can get into our lungs and brains. So how good are they at cleaning our clogged up skies? Following on from our original programme, CrowdScience was contacted by a team of researchers in the UK who claim tress may be as much as 50 times better than previously thought at mopping up particles, and learn that hedges may help us stay healthy on roads. Also in the programme, we discover what pollutants are doing to our brains and reveal research which shows that keeping house plants can significantly reduce pollution inside the home. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Marnie Chesterton Producer: Marijke Peters