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<p>Tropospheric ozone (<span class="inline-formula">O₃</span>) is an important air pollutant that affects human health, ecosystems, and climate. The contributions of <span class="inline-formula">O₃</span> precursor emissions from different geographical source regions to the <span class="inline-formula">O₃</span> concentration can help to quantify the effects of local versus remotely transported precursors on the <span class="inline-formula">O₃</span> concentration in a certain area. This study presents a “tagging” approach within the WRF-Chem model that attributes <span class="inline-formula">O₃</span> concentration in several European receptor regions to nitrogen oxide (<span class="inline-formula">NO_<i>x</i></span>) emissions from within and outside of Europe during April–September 2010. We also examine the contribution of these different precursor sources to various <span class="inline-formula">O₃</span> metrics and their exceedance events. Firstly, we show that the spatial distributions of simulated monthly mean MDA8 from tagged <span class="inline-formula">O₃</span> source regions and types for late spring, summer, and early autumn 2010 varies with season. For summer conditions, <span class="inline-formula">O₃</span> production is dominated by national and intra-European sources, while in the late spring and early autumn intercontinental transported <span class="inline-formula">O₃</span> is an important contributor to the total <span class="inline-formula">O₃</span> concentration. We have also identified shipping activities in the Mediterranean Sea as an important source of <span class="inline-formula">O₃</span> for the Mediterranean countries, as well as the main contributor to high modelled MDA8 <span class="inline-formula">O₃</span> concentration in the Mediterranean Basin itself. Secondly, to have a better understanding of the origin of MDA8 <span class="inline-formula">O₃</span> exceedances, we compare modelled and observed values of MDA8 <span class="inline-formula">O₃</span> concentration in the Po Valley and Germany–Benelux receptor regions, revealing that the contribution from local sources is about 41&thinsp;% and 38&thinsp;% of modelled MDA8 <span class="inline-formula">O₃</span> during the exceedance days, respectively. By examining the relative contributions of remote <span class="inline-formula">NO_<i>x</i></span> sources to modelled and observed <span class="inline-formula">O₃</span> exceedance events, we determine that model underrepresentation of long-range <span class="inline-formula">O₃</span> transport could be contributing to a general underestimation of modelled <span class="inline-formula">O₃</span> exceedance events in the Germany–Benelux receptor region. Thirdly, we quantify the impact of local vs. non-local <span class="inline-formula">NO_<i>x</i></span> precursors on <span class="inline-formula">O₃</span> production for each European receptor region using different <span class="inline-formula">O₃</span> metrics. The comparison between mean, MDA8 and 95th percentile <span class="inline-formula">O₃</span> metrics accentuates the importance of large contributions from locally emitted <span class="inline-formula">NO_<i>x</i></span> precursors to the high end of the <span class="inline-formula">O₃</span> distribution. When we compare the vegetation and health metrics, we notice that the SOMO35 and AOT40 indexes exhibit rather similar behaviour, while the W126 index accentuates the importance of local emissions. Overall, this study highlights the importance of a tagging approach to quantify the contribution of local and remote sources to the MDA8 <span class="inline-formula">O₃</span> concentration during several periods as well to different <span class="inline-formula">O₃</span> metrics. Moreover, this method could be applied to assess different mitigation options.</p>