Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Spain, The is focused on quantifying the interactive effects of ozone and nitrogenous compounds on Mediterranean vegetation and defining air pollutant threshold values (critical loads and levels) for the protection of ecosystems. Our group has experience on atmospheric nitrogen deposition, particularly dry deposition. We are investigating the interactive effects of ozone and nitrogen enrichment on yield and quality of crops. We are interested in the influence of climate change and air pollution on carbon and nitrogen cycles and soil-plant-atmosphere interactions in Mediterranean forests ecosystems and crops. This group has hold different agreements since 2001 with the Spanish Ministry of Environment with the objective to apply and adapt the methodologies developed under the LRTAP Convention.