Surface - atmosphere exchange processes of trace gases and particulate matter. The research has been applied to ozone, acid deposition, the global biogeochemical cycle of nitrogen, emissions of greenhouse gases, atmospheric aerosols and effects of pollutants on vegetation. He also has a particular interest in the policy applications of air quality research and has been closely involved with policy teams in the UK, the EU and UNECE.
David has been a contributing author to more than 230 refereed publications in addition to contributions to book chapters and conference proceedings, and has an H index of 56. He was awarded an Honorary Professorship at the University of Nottingham in 1991, became a Fellow of the Royal Society of Edinburgh in 1999, and a Fellow of the Royal Society of London in 2002. In 2005 he was awarded a CBE for services to research into Atmospheric Pollution.