Maybe a salicylic acid cleanser is part of your nightly skin care routine to keep breakouts at bay. Or perhaps you diligently use an SPF moisturizer during the day because you know sun protection ...

Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K. Department of Physics, Cavendish Laboratory, University of Cambridge, JJ ...