In the open sea pollution levels are generally low, but along the Norwegian coast there are a number of problem areas with high levels of hazardous substances in seabed sediments. This particularly applies to harbours and fjords affected by emissions from industry.
Clean up measures have improved the state of the environment in some areas, for example in Sørfjorden on the west coast. However, new studies have revealed an increasing number of problem areas.
The content of environmentally hazardous substances in mussels is a good indicator of the state of the environment in a fjord. Surveys of mussels in polluted fjords show an improvement from 1993 to 2002.
In 2002 the basis for producing the aggregated index above was changed. New stations and parameters were introduced to improve the index. The data for 2002-2010 are therefore not directly comparable with data for earlier years. To illustrate this, the 2002 data is shown with both the new and the old index.
