What should the initial readings at the locations be less than to ensure accurate substrate correction?

To ensure accurate substrate correction in lead risk assessment, the initial readings at the locations should be less than 2.5 mg/cm². This threshold is critical because it helps maintain the integrity and accuracy of the sampling process. When lead dust levels are at or below this concentration, it indicates that the environment is at a reasonably low risk for lead exposure, allowing for more reliable corrective measures and proper evaluation of lead hazards.

Furthermore, if the initial readings were higher than this value, it would signify potential risks or contamination that would require further investigation and remediation. These considerations are crucial in ensuring that the lead risk assessments are both effective and adhere to safety standards, preventing any oversight that could lead to health hazards for individuals, especially children.