Dust clearance value on floors is expressed in which unit?

Dust clearance value on floors is expressed in which unit?

• A. Micrograms per square foot (ug/ft2)
• B. Micrograms per gram (ug/g)
• C. Micrograms per square foot (ug/ft2)
• D. Micrograms per cubic meter (ug/m3)

Answer: (C)

Dust clearance value on floors is expressed as micrograms per square foot. This reflects surface loading: you wipe a defined floor area and measure how many micrograms of lead are present on that area. It’s not an air concentration (which would use micrograms per cubic meter) and not a mass-per-mass value (which would use micrograms per gram). Using per-area units allows consistent reporting across different room sizes and directly relates to potential contact with contaminated dust on the floor. For example, if a 1 square foot wipe yields 6 micrograms of lead, the floor clearance value is 6 μg/ft^2.

Dust clearance value on floors is expressed as micrograms per square foot. This reflects surface loading: you wipe a defined floor area and measure how many micrograms of lead are present on that area. It’s not an air concentration (which would use micrograms per cubic meter) and not a mass-per-mass value (which would use micrograms per gram). Using per-area units allows consistent reporting across different room sizes and directly relates to potential contact with contaminated dust on the floor. For example, if a 1 square foot wipe yields 6 micrograms of lead, the floor clearance value is 6 μg/ft^2.