OZONE CONCENTRATIONS IN URBAN AND RURAL-FORESTED AREAS IN THE BASQUE COUNTRY (SPAIN)

In response to general concern about atmospheric pollution and forest decline, a comprehensive program was created in 1985 to assess the dep osition levels of atmospheric pollutants and their effects in Pinus ra diata plantations in the Basque Country (Spain). There is a serious co ncern about the environmental impact of ozone (O-3) on vegetation and on human health both in urban and rural areas. We present data from 19 93-1995 measures of O-3 levels near Pinus radiata forested areas, and in urban sites of the Bilbao metropolitan area. To quantify the O-3 ex posures, hourly average O-3 concentration data were characterized in t he Barambio and the Berganza sites (rural-forested areas), and in the Basauri and the Getxo sites (Bilbao metropolitan area). The Berganza a nd the Barambio sites experienced more occurrences of hourly average c oncentrations > 75 and > 100 ppb than the Basauri and the Getxo sites. The AOT40 exposure values in the two forested sites were 2-4 times hi gher that the critical levels, while in the two urban sites AOT40 were lower or equal to the critical values. The lower-elevation site of Be rganza and the urban sites experienced a greater percentage of its O-3 exposure during daylight hours (08:00-20:00 h) than the Barambio site . The results indicate an overall increase on the average values of th e O-3 concentrations since 1993 in the forested sites, while in the ur ban sites, the values are variable.