The graphs are based on: the 93.15 percentile of the daily maximum of the running 8-h mean O3 concentrations (in μg/m3),
corresponding to the 26th highest as defined by the target value, and for the various types of stations (top); AOT40
concentrations (in (μg/m3).h) measured in rural stations in the EU for the protection of vegetation (accumulated over May to
July) (bottom left); and AOT40 concentrations (in (μg/m3).h) measured in rural stations in the EU for the protection of forests
(accumulated over April to September) (bottom right). The CLRTAP critical level for the protection of forests (Mills et al., 2011) is
set at 10 000 (μg/m3).h for AOT40 (the accumulated dose of O3 over a threshold of 40 ppb, equivalent to 80 μg/m3, from 1 April
to 30 September).
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