Which item does NOT meet the threshold for surface contamination per the EPA?

The threshold for surface contamination set by the EPA is critical for identifying lead hazards in residential and child-occupied facilities. The acceptable levels are based on extensive studies about health impacts and potential exposure risks. The thresholds for floors, window sills, and window wells are defined specifically to mitigate the dangers associated with lead exposure, particularly for children who are at greater risk.

The value of 10 μg/ft² for floors, 250 μg/ft² for windows, and 400 μg/ft² for window wells are established limits indicating concern for lead contamination. These measures reflect areas where children are likely to encounter lead dust, either through play or everyday activities, making the thresholds particularly relevant for the health and safety of young occupants.

In contrast, the limit of 500 μg/ft² on walls exceeds the established guidelines for lead contamination. Wall surfaces are generally not considered as high-risk exposure areas as floors and windows, primarily because they are less frequently interacted with by children. As a result, this threshold does not meet EPA standards for hazardous surface contamination, reinforcing that while lead hazards are a concern throughout a dwelling, certain areas carry higher weight in terms of safety standards and exposure risk assessments.