SMALL-SCALE SPATIAL VARIABILITY OF PARTICULATE MATTER LESS-THAN-10-MU-M (PM10) AND NITROGEN-DIOXIDE

Epidemiological studies often rely only on data from a single monitori ng station at a study site. However, significant small-scale spatial g radients for air pollutants are inevitable and one monitoring station cannot be representative for the entire population living in the study region. Small- scale spatial gradients (horizontally and vertically) of particulate matter < 10 mu m (PM10) and NO2 were examined along a r oadside in Zurich during the winter and summer seasons (1994-1995). Ho rizontal and vertical concentration gradients for PM10 were about 13% (spatial coefficient of variation), and for NO2 about 15%. For PM10, t he effect of season on the horizontal and vertical gradient was small. For NO2, the small-scale spatial gradients were highly influenced by season: during the spring-summer season, spatial gradients were much g reater than during the autumn-winter season. This implies that future monitoring programmes, should include more monitoring sites for PM10 a nd, especially for NO2, the spring-summer season should include far mo re spatial resolution. (C) 1997 Elsevier Science Ltd.