The dataset consists of proportions of ozone injured or senesced leaves from a study which investigated how the presence of competing species in a community affects these two common responses to ozone. Monocultures and mixtures of Trifolium repens and Lolium perenne were grown in large containers and were exposed in solardomes to either a rural episodic ozone profile (AOT40 (Accumulated Ozone Threshold exposure of 40 parts per billion) of 12.86 ppm h) or control conditions (AOT40 of 0.02 ppm h) for 12 weeks. The proportion of ozone-injured or senesced leaves was determined in different regions of the canopy, the upper canopy (>14cm high), the canopy edge and the inner canopy, by separating injured/senesced leaves from healthy leaves. The experiment was carried out at the CEH Bangor Air Pollution Facility. This work was funded by the Centre for Ecology & Hydrology Integrating Fund Initiative Full details about this dataset can be found at https://doi.org/10.5285/bc4d0325-b67b-4fff-a14b-6e06edf397bd