Final dust wipe sample results must be reported in which unit?

Final dust wipe sample results must be reported in which unit?

• A. ug/ft2
• B. mg/m2
• C. ppm
• D. ng/cm2

Answer: (A)

Final dust wipe results are reported in micrograms per square foot because the amount of lead on a surface is a mass per area measurement. This unit directly mirrors the clearance criteria used by regulators, making it easy to compare the measured contamination to the specified thresholds for interior surfaces. While ng/cm^2 is a valid unit and can be converted (1 ng/cm^2 ≈ 0.929 μg/ft^2), the standard reporting convention in this context is μg/ft^2, which keeps data consistent with the regulatory standards. Using other units like mg/m^2 or ppm doesn’t align with the surface-area-based criteria used for lead dust in interiors. For example, 50 ng/cm^2 is about 46.5 μg/ft^2, illustrating the same level of contamination expressed in the preferred unit.

Final dust wipe results are reported in micrograms per square foot because the amount of lead on a surface is a mass per area measurement. This unit directly mirrors the clearance criteria used by regulators, making it easy to compare the measured contamination to the specified thresholds for interior surfaces. While ng/cm^2 is a valid unit and can be converted (1 ng/cm^2 ≈ 0.929 μg/ft^2), the standard reporting convention in this context is μg/ft^2, which keeps data consistent with the regulatory standards. Using other units like mg/m^2 or ppm doesn’t align with the surface-area-based criteria used for lead dust in interiors. For example, 50 ng/cm^2 is about 46.5 μg/ft^2, illustrating the same level of contamination expressed in the preferred unit.