Urban air pollution and forests

Close to city forests have distinct recreational purposes, according to air pollution conditions. There are influenced by internal and external factors. The differences in air pollution structure between two cities and two forests which are close to the cities in Southwest Germany were investigated. The results are based on data supplied by official stations for the monitoring of air quality, in this case for the pollutants NO, NO2 and O3 in the period 1992 through 1996. The results for both weekdays and weekends, presented as average diurnal cycles of the analysed air pollutants, reveal that concentra-tions of NO and NO2 were much higher in urban areas. Levels of concentra-tion of O3, however, were higher in the close to city forests. The differ-ences in air quality depend on the specific location of land use investigated as well as on the situation regarding pollutant emission within the cities.