Think of the Grow Gorgeous Defence Anti-Pollution Leave-In Spray (£23) a bit like a sunscreen for your hair, except that instead of blocking UV rays, it helps protect strands from all the dirt and grime floating around in the air. Meant to be sprayed on towel-dried hair, this spray is does what a leave-in conditioner does (it contains panthenol, glycerin, amino acids, and sunflower sprout extract to help hydrate and add shine), but then goes the extra step of creating a protective layer around the hair thanks to a proprietary ingredient complex that the brand calls the "polysaccharide matrix".