Concentration status for the target value threshold for protection of forests, 2011 https://www.eea.europa.eu/data-and-maps/daviz/aot-forest-air Distribution of rural stations by thresholds of AOT40 concentrations for the year 2011. AOT40 concentrations for the protection of forest is the accumulated dose of hourly concentrations of O3 over a threshold of 40 ppb, equivalent to 80 μg/m3, accumulated over five month (April to September). en Plone Concentration status for the target value threshold for protection of forests, 2011 https://www.eea.europa.eu/eea-print-logo.gif https://www.eea.europa.eu/data-and-maps/daviz/aot-forest-air