How the trees in your local park help protect you from disease

On your next visit to the park, try and count all the different species you can see. Away from the closely mown grass, you might spot wildflowers attended by pollinating insects, like bees, wasps and hoverflies. Overhead there are the gnarled branches of mature trees, some of which will have lived for hundreds of years, providing food and refuge for generations of fungi and insects.

You may find yourself immersed in the chorus of songbirds fervently competing for mates. There will undoubtedly be fleet-footed mammals scurrying in the bushes and amphibians hiding under logs.

But there’s also another world of wildlife floating all around you. This is the biodiversity that we can’t see with the naked eye – the secret life of the air we breathe.