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Surface ozone data from 25 European low-altitude sites and mountain sites located between 79 deg. N and 28 deg. N were studied. The analysis covered the time period March 1989-February 1993. Average summer and winter O3 concentrations in the boundary layer over the continent gave rise to gradients that were strongest in the north-west to south-east direction and west-east direction, respectively. Wintertime O3 ranged from 19 to 27 ppb over the continent, compared to about 32 ppb at the western border, while for summer the continental O3 values ranged between 39 and 56 ppb and the oceanic mixing ratios were around 37 ppb. In the lower free troposphere average wintertime O3 mixing ratios were around 38 ppb,with only an 8 ppb difference between 28 deg. N and 79 deg. N. For summer the average O3 levels decreased from about 55 ppb over Central Europe to 32 ppb at 79 deg. N. In addition, O3 and Ox (= O3 + NO2) in polluted and clean air were compared. The amplitudes of the seasonal ozone variations increased in the north-west to south-east direction, while the time of the annual maximum was shifted from spring (at the northerly sites) to late summer (at sites in Austria and Hungary), which reflected the contribution of photochemical ozone production in the lower parts of the troposphere. [ABSTRACT FROM AUTHOR]

The ongoing program Clean Air for Europe (CAFE) is an initiative from the EU Commission to establish a coordinated effort to reach better air quality in the EU. The focus is on particulate matter as it has been shown to have large impact on human health. CAFE requested that WHO make a review of the latest findings on air pollutants and health to facilitate assessments of the different air pollutants and their health effects. The WHO review project on health aspects of air pollution in Europe confirmed that exposure to particulate matter (PM), despite the lower levels we face today, still poses a significant risk to human health. Using the recommended uniform risk coefficients for health impact assessment of PM, regardless of sources, premature mortality related to long-range transported anthropogenic particles has been estimated to be about 3500 deaths per year for the Swedish population, corresponding to a reduction in life expectancy of up to about seven months. The influence of local sources is more difficult to estimate due to large uncertainties when linking available risk coefficients to exposure data, but the estimates indicate about 1800 deaths brought forward each year with a life expectancy reduction of about 2-3 months. However, some sectors of the population are exposed to quite high locally induced concentrations and are likely to suffer excessive reductions in life expectancy. Since the literature increasingly supports assumptions that combustion related particles are associated with higher relative risks, further studies may shift the focus for abatement strategies. CAFE sets out to establish a general cost effective abatement strategy for atmospheric particles. Our results, based on studies of background exposure, show that long-range transported sulfate rich particles dominate the health effects of PM in Sweden. The same results would be found for the whole of Scandinavia and many countries influenced by transboundary air pollution. However, several health studies, including epidemiological studies with a finer spatial resolution, indicate that engine exhaust particles are more damaging to health than other particles. These contradictory findings must be understood and source specific risk estimates have to be established by expert bodies, otherwise it will not be possible to find the most cost effective abatement strategy for Europe. We are not happy with today's situation where every strategy to reduce PM concentrations is estimated to have the same impact per unit change in the mass concentration. Obviously there is a striking need to introduce more specific exposure variables and a higher geographical resolution in epidemiology as well as in health impact assessments.