The term "suspected contaminated sites" refers to areas suspected of being contaminated. Contaminated sites are, for example, disused landfill sites for municipal or commercial waste (old landfills) or disused facilities, armaments sites and operating areas where environmentally hazardous substances have been handled (old sites), insofar as these have caused harmful soil changes or other hazards. Data on contaminated sites and suspected contaminated sites are summarized in the register of contaminated sites.

According to the Environmental Information Act (UIG), every person is entitled to free access to environmental information held by a body with a duty to provide information. In Lower Saxony, the UIG applies in conjunction with the Lower Saxony Environmental Information Act (NUIG). Access can be granted by providing information, granting access to files or by other means. Any person can therefore obtain information from the register of contaminated sites on request. Such information is important, for example, when buying or selling a property, for construction or demolition projects and for groundwater use in the vicinity of contaminated sites. However, in many cases the information on a contaminated site or suspected contaminated site may involve personal data. The competent authority must then check whether the interests of the person concerned would be significantly impaired by the disclosure of the information; if necessary, it must carry out a balancing exercise.