Spatial depiction of exceedances and corresponding exceedance magnitude. Exceedance magnitude is defined as the difference between the shale gas scenarios and base case when an exceedance occurs, and is an indicator of the robustness of shale gas emissions on an exceedance. Exceedances are displayed as filled dots at the station locations where they occur, in μg m^–3, over JJA, applying the WHO guideline for O₃ as the threshold (100 μg m^–3). For stations which experienced more than one exceedance, the maximum exceedance magnitude is shown. The top left-hand corner of each plot indicates the particular scenario, and the top right-hand corner displays the maximum exceedance magnitude value experienced over the domain and simulation period. DOI: https://doi.org/10.1525/elementa.387.f11