[The outer environment--now and then].

Hazardous environmental factors in Norway have changed considerably over the last decades, often for the better. During the last five-year period, water-works serving 800,000 Norwegians have been renovated. The earlier high levels of sulphur dioxide and lead in urban air are now very low, whereas suspended particulate matter and nitrogen oxides continue to be at levels which can induce adverse health effects. Radon and tobacco smoke are now important indoor contaminants. Moisture-induced damage in dwellings may lead to health problems; the extent of such damage is, however, not known. A number of fjords are still contaminated with metals, PAH (polycyclic aromatic hydrocarbons), PCB (polychlorinated biphenyls) and dioxins, even though industrial discharge to water and air has been greatly reduced. Body burdens of DDT, PCB and dioxins have been markedly lowered over time. There is a continuous increase in the use of chemicals, though the chemicals are better tested and controlled than before. The total volume of pesticides used has fallen over the last three decades. There are no clear changes over the last 15 to 20 years in perceived noise exposure.