The work of Prof. Sutton focuses on ammonia and the wider nitrogen cycle, linking disciplines from micrometeorology and atmospheric chemistry to plant ecology and policy analysis, leading to new understanding and quantitative models. Prof. Sutton has led a series of key national and international collaborative projects including the NitroEurope Integrated Project (€28M, 64 partner institutes) for the EU. A key outcome was the first European Nitrogen Assessment (Cambridge University Press).