In the emergency area, they collect water, soil and air samples to tell the extent of contamination according to Federal Water Pollution Control Act. Regular collection and analysis of these samples during the control period by the monitoring team helps them know the progress and safety of the area. In cases where they have to close down an area, they analyze the area regular to check on the decline of contamination.
In cases dealing with radiology contamination they may have to close the area for many years or for ever, reasons been the long period radiological contaminants take to decay. They analyze food, water and air in the area and decide whether it is safe for any living thing to live in. quarantine of the area involves the advice of people to stay indoors or the complete evacuation of the area.