Past, present and future concentrations of ground-level ozone and potential impacts on ecosystems and human health in northern Europe

摘要

This review summarizes new information on the current status of ground-level ozone in Europe north of the Alps. There has been a re-distribution in the hourly ozone concentrations in northern Europe during 1990-2015. The highest concentrations during summer daytime hours have decreased while the summer night-time and winter day- and night-time concentrations have increased. The yearly maximum 8-h mean concentrations ([O_3]_(8h,max)). a metric used to assess ozone impacts on human health, have decreased significantly during 1990-2015 at four out of eight studied sites in Fennoscandia and northern UK. Also the annual number of days when the yearly [O_3]_(8h,max) exceeded the EU Environmental Quality Standard (EQS) target value of 60 ppb has decreased. In contrast, the number of days per year when the yearly [O_3]_(8h,max) exceeded 35 ppb has increased significantly at two sites, while it decreased at one far northern site. [O_3]_(8h,max) is predicted not to exceed 60 ppb in northern UK and Fennoscandia after 2020. However, the WHO EQS target value of 50 ppb will still be exceeded. The AOT40 May-July and AOT40 April-September metrics, used for the protection of vegetation, have decreased significandy at three and four sites, respectively. The EQS for the protection of forests, AOT40 April-September 5000 ppb h, is projected to no longer be exceeded for most of northern Europe sometime before the time period 2040-2059. However, if the EQS is based on Phytotoxic Ozone Dose (POD), POD_1, it may still be exceeded by 2050. The increasing trend for low and medium range ozone concentrations in combination with a decrease in high concentrations indicate that a new control strategy, with a larger geographical scale than Europe and including methane, is needed for ozone abatement in northern Europe.