Probability of positive or negative trends averaged across regions NDGT70 (days/yr) for 2000–2014. Trends for stations within the 15 regions shown in Figure 3 (and some sub-regions) The number of sites (N) are shown for each region. The colour scale for increasing and decreasing ozone levels over time and associated p-values is the same as in Figure 8. DOI: https://doi.org/10.1525/elementa.273.f9b