MOTTLES is supported by the Programme LIFE15 and proposes new critical levels for forest protection against Ozone. This issue arises because European standards to protect vegetation from this air pollutant are currently based on O3 concentration in the atmosphere, not on the stomatal ozone fluxes, e.g. how much ozone is effectively taken by plants. The long-term monitoring network established by Mottles will allow to combine real time O3 concentrations, meteorological parameters and the plant response indicators for ozone on vegetation (visible ozone injury, crown defoliation and hourly radial growth), hence to estimate stomatal fluxes. Therefore, this novel monitoring strategy will establish new scientifically-sound critical levels for protecting forests against ozone pollution to be used as new legislative standards in Europe. The Mottles network is located in three European countries: Italy, France and Romania, so other than CNR and CREA for Italy, the partners involved are ACRI-HE and GIEFS for France, and INDCS for Romania. Other info: http://mottles.ipsp.cnr.it/.