[National Observation Network for Air Pollutants. Measurements up to now--planned extensions].

Since 6 years a Swiss national emission monitoring network measures several air pollutants (sulfur dioxide, nitrogen oxides, ozone, carbon monoxide, suspended particulates, particle deposition and precipitations) at 8 sites with different pollution levels (Dübendorf, Zürich, Basel, Sion, Payerne, Lugano, Tänikon, Jungfraujoch). The emission concentrations of sulfur dioxide, nitrogen dioxide and ozone exceed the limit values proposed by federal legislation at several sites, though the monitoring stations are not located at sites with extreme exposure. At present the network is extended for two or three new stations in forests as a part of a Swiss research programme concerning air pollution and forest damages. A further extension of the NABEL will comprise improvements of the measuring programme at the existing stations as well as new stations.