Which unit is utilized to express lead levels in dust?

The correct choice for expressing lead levels in dust is represented using micrograms per square foot (ug/sq ft). This unit is specifically designed for measuring the concentration of contaminants, such as lead, on surfaces. Dust sampling protocols often focus on surface contamination, and expressing results as micrograms per square foot provides a clear understanding of the amount of lead present on a given area.

In the context of lead dust abatement and environmental health, this measurement is crucial as it directly relates to potential exposure risks and helps in determining compliance with safety standards. Using ug/sq ft allows professionals to assess the effectiveness of abatement efforts and ensure that surfaces are safe for occupants.

Other units listed do not appropriately measure lead levels in dust. For instance, milligrams per square foot (mg/sq ft) could be used but is less standard in lead dust reporting. Parts per million (ppm) typically applies to concentrations in air or liquid samples, while micrograms per cubic meter (ug/m³) is generally used for airborne lead concentrations rather than surface dust. Thus, utilizing micrograms per square foot is the most relevant and precise method for determining lead levels in dust.