NICK HEWITT, PHD, is Distinguished Professor of Atmospheric Chemistry at Lancaster University, UK. His main research interests are in understanding how the biosphere and the atmosphere interact, how emissions of trace gases from the surface affect the composition and chemistry of the atmosphere, and how the changing atmospheric environment affects the world we live in. ANDREA V. JACKSON, PHD, recently retired as Professor of Student Education and Engagement at the University of Leeds, UK. As well as conducting research in atmospheric chemistry, she worked with the UK's National Centre for Atmospheric Science on the development of their education and training programmes.