CDPH Lead Inspector/Assessor California State Practice Exam

What unit of measurement is used for lead in wipe samples?

1. Micrograms per square foot (μg/f2)

2. Milligrams per cubic meter (mg/m3)

3. Parts per billion (ppb)

4. Milligrams per square meter (mg/m2)

The correct answer is: Micrograms per square foot (μg/f2)

The correct answer is micrograms per square foot (μg/ft²). This unit of measurement is specifically utilized for assessing lead contamination in surfaces, particularly in the context of wipe sampling in lead hazard evaluations. Wipe samples are designed to evaluate the presence of lead dust or residue on surfaces, such as floors, windowsills, and other areas where lead may accumulate. Micrograms per square foot allows for a clear understanding of the amount of lead present over a defined area, which is critical for evaluating potential exposure risks, especially in settings such as homes or schools that may have lead-based paint or other lead sources. Other units, such as milligrams per cubic meter (mg/m³), are typically used for measuring airborne lead concentrations, while parts per billion (ppb) is commonly applied in water quality testing. Milligrams per square meter (mg/m²) is less relevant for wipe samples, as it reflects a measure more suited to solid deposits over a larger surface area or material weighing. Thus, micrograms per square foot is the most appropriate measurement for analyzing lead contamination in wipe samples.