India, June 8 -- Planting the right trees in the right places isn't just about beautifying the capital city of Delhi - it's about building a living, breathing defence against one of the world's worst urban air pollution crises

Trees, shrubs, and grasses do far more than add greenery to grey cityscapes. Vegetation intercepts airborne particles on leaves, branches, bark, and stems, physically reducing the amount of dust and pollutants residents inhale. Dense canopies stabilise exposed soil, cutting down on wind-blown dust resuspension - one of Delhi's major pollution contributors. Plants also absorb gaseous pollutants such as oxides of sulphur and nitrogen directly through their stomata.

Additionally, trees add surface roughness that prom...