Ozone concentrations in urban and rural‐forested areas in the basque country (Spain)

Abstract

In response to general concern about atmospheric pollution and forest decline, a comprehensive program was created in 1985 to assess the deposition levels of atmospheric pollutants and their effects in Pinus radiata plantations in the Basque Country (Spain). There is a serious concern about the environmental impact of ozone (O₃) on vegetation and on human health both in urban and rural areas. We present data from 1993–1995 measures of O₃ levels near Pinus radiata forested areas, and in urban sites of the Bilbao metropolitan area. To quantify the O₃ exposures, hourly average O₃ concentration data were characterized in the Barambio and the Berganza sites (rural‐forested areas), and in the Basauri and the Getxo sites (Bilbao metropolitan area). The Berganza and the Barambio sites experienced more occurrences of hourly average concentrations >75 and >100 ppb than the Basauri and the Getxo sites. The AOT40 exposure values in the two forested sites were 2–4 times higher that the critical levels, while in the two urban sites AOT40 were lower or equal to the critical values. The lower‐elevation site of Berganza and the urban sites experienced a greater percentage of its O₃ exposure during daylight hours (08: 00–20: 00 h) than the Barambio site. The results indicate an overall increase on the average values of the O₃ concentrations since 1993 in the forested sites, while in the urban sites, the values are variable.

Key words:

• Ozone
• forest
• urban area
• critical levels
• pollution