Take some time for yourself with soothing classical music from the mindful mix, the Science of

Happiness Podcast.

For the last 20 years I've dedicated my career to exploring the science of living a happier more meaningful life and I want

to share that science with you.

And just one thing, deep calm with Michael Mosley.

I want to help you tap in to your hidden relaxation response system and open the door to that

calmer place within. Listen on BBC Sounds. Hello and this is And welcome to Crowd Science from the BBC World Service.

I'm Marnie Chesterton, and this is the program that trots the globe,

or this week pounds the pavement, to find answers to your science questions.

On today's show, we're continuing a quest to find out

how greenery can clean our air which all started with this listener question from

Brazil. Hello my name isio. My question for crown sciences, how good are trees at reducing air pollution?

And could they be bad at it?

Kio's from Brazil's biggest city, Sao Paulo, where air pollution is almost double the safe

level, and he first wrote to us at the start of this year to see of trees, which are very

good at hovering up carbon dioxide, are also useful in dealing with the other

stuff we don't want in the skies.

Back in February, we made a show answering Caio's question, which sparked a bit of a debate in the scientific community about just how much

trees can do. Researchers have different ideas about all sorts of aspects, from

the best type of tree to deal with the problem

to the best way to measure how much pollution trees remove and in today's

program we'll be returning to some of the experts we originally heard from, as well as talking to others who've reached very different conclusions.

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