What are the required size bounds for a wipe sample?

What are the required size bounds for a wipe sample?

• A. between 0.5 ft2 and 5 ft2
• B. at least 0.1 ft2 and no more than 2 ft2
• C. exactly 1 ft2
• D. no minimum and no maximum

Answer: (A)

Wipe sampling reports lead contamination as mass per unit area, so the area you wipe must be chosen to give a reliable, comparable measurement. If the wipe is too small, there may not be enough lead collected to measure accurately, leading to non-detects or highly variable results. If the wipe is too large, you can mix dust from different surfaces and make the sample harder to collect cleanly, which can distort the per-square-foot loading value and complicate analysis. The specified bounds—0.5 square feet up to 5 square feet—provide a practical balance: small enough to target a single surface type and large enough to yield a measurable amount of lead for typical lab methods, while keeping results comparable to standard EPA criteria expressed as micrograms per square foot.

Wipe sampling reports lead contamination as mass per unit area, so the area you wipe must be chosen to give a reliable, comparable measurement. If the wipe is too small, there may not be enough lead collected to measure accurately, leading to non-detects or highly variable results. If the wipe is too large, you can mix dust from different surfaces and make the sample harder to collect cleanly, which can distort the per-square-foot loading value and complicate analysis.

The specified bounds—0.5 square feet up to 5 square feet—provide a practical balance: small enough to target a single surface type and large enough to yield a measurable amount of lead for typical lab methods, while keeping results comparable to standard EPA criteria expressed as micrograms per square foot.