What does a positive XRF result indicate?

A positive XRF (X-ray fluorescence) result indicates that lead is present at or above the established standards for lead exposure or contamination. This portable testing method is widely used in lead risk assessment because it provides immediate feedback on the presence and concentration of lead in various materials such as paint, soil, and dust.

When interpreting the results of an XRF test, a positive reading signifies that the lead levels exceed safe exposure thresholds set by regulatory agencies. These standards are established to protect human health, particularly for vulnerable populations like children, who are more susceptible to the harmful effects of lead exposure. Therefore, a positive result is critical for identifying situations where remediation efforts are needed to reduce lead hazards and ensure safety.

In contrast, the other options refer to scenarios where lead is either at acceptable levels, undetected, or completely absent, which would not warrant the same level of concern or immediate action.