Obtained his BA in Natural Sciences (Chemistry) and PhD in Physical Chemistry from the University of Cambridge. His PhD research concerned laboratory studies of reactions of iodine species in the marine atmosphere. In 1999 he moved to the California Institute of Technology, based at the NASA Jet Propulsion Laboratory, studying polar stratospheric ozone hole formation. In 2001 he moved to the School of Chemistry at the University of Leeds, where his research involved field measurements of tropospheric radical species. He joined the University of Birmingham in 2007, where he is Professor of Atmospheric Science and lead PI for WM-Air: Clean Air Science for the West Midlands. He was Head of School for Geography, Earth & Environmental Sciences, 2016 - 2020.