Residents are being advised that land surveys are due to be carried out in a number of areas in County Durham.
Durham County Council will be conducting the surveys as part of its legal responsibilities under the Environmental Protection Act 1990 to identify potentially contaminated land.
Surveys are to be carried in 10 locations and letters to people living in those areas are being sent out later this week.
Joanne Waller, head of environment, health and consumer protection at Durham County Council, said: “These surveys are being done as part of our legal responsibilities.
“We would like to reassure people that there is no current evidence which suggests that any land is actually contaminated or that there is any risk to public health.”
The sites being surveyed have been identified based on the fact that they have, at some time in the past, been used for industrial purposes.