What does worst-case sampling require a risk assessor to do?

Worst-case sampling requires a risk assessor to conduct a walkthrough to identify the highest risk dwellings because this approach aims to ensure that the assessment captures conditions that could potentially lead to the highest exposure to lead hazards. By focusing on dwellings with the most significant risk factors, the risk assessor can gather data that represents the worst-case scenario, which is crucial for developing appropriate management or remediation strategies.

This method typically involves examining factors such as the age of the property, the condition of the paint, the presence of lead pipes, and other relevant environmental indicators that might contribute to lead exposure. By prioritizing higher-risk environments, the risk assessor can provide more accurate results and recommendations that effectively address potential lead hazards in homes, especially those where vulnerable populations, such as children, reside.

In comparing the other options, surveying only the lowest risk dwellings would not provide an accurate assessment of potential lead exposure, as it may overlook problematic areas. Testing all dwelling units without selection could lead to unnecessary resource allocation and doesn't focus on the most pressing concerns. Focusing entirely on exterior paint ignores other potential sources of lead exposure that could be present in interior environments, thus undermining the comprehensive nature of the assessment.