Why must the sample area be cleaned prior to collecting a sample?
Cleaning the sampling area reduces the chance of sample contamination. For example: you are testing the windows, walls and doors of a room. The window was painted with lead based paint but the walls and doors were not. Lead dust from the windows can settle on the walls or doors and when you take the sample from the wall or a door you may get a false positive result. If you clean the wall or door surface before sampling, you remove the dust originating from the window and your test results will be more accurate.
