What are EPA requirements for clearance sampling in multifamily housing of 20 units or more?

What are EPA requirements for clearance sampling in multifamily housing of 20 units or more?

• A. Sample every dwelling in the building
• B. Clearance levels are not required for multifamily housing
• C. A sufficient number of residential dwellings are selected for dust sampling to provide a 95 percent level of confidence that no more than 5% or 50 of the residential dwellings in the randomly sampled population exceed the appropriate clearance levels
• D. Use only interior dust samples for clearance

Answer: (C)

In multifamily housing, clearance testing uses a statistically valid sampling approach rather than testing every unit. The idea is to select a sufficient number of dwellings at random so you can estimate, with high confidence, how many units in the building would fail the clearance levels if you tested the entire population. The goal is to have a 95 percent level of confidence that no more than a small portion of units—specifically 5 percent of the residential dwellings, or up to 50 dwellings, whichever cap applies in the guidance—exceed the applicable clearance levels. If the sampled units all meet clearance within that tolerance, the building is considered to have achieved clearance. This approach balances practicality with reliability: it avoids the impracticality of testing every unit while still providing strong assurance that the overall building is safe. It’s not correct to require sampling every unit, or to say clearance levels aren’t required, and clearance sampling isn’t restricted to interior dust samples alone; surface dust from pertinent areas (like floors and window sills) in the sampled units is typically used.

In multifamily housing, clearance testing uses a statistically valid sampling approach rather than testing every unit. The idea is to select a sufficient number of dwellings at random so you can estimate, with high confidence, how many units in the building would fail the clearance levels if you tested the entire population. The goal is to have a 95 percent level of confidence that no more than a small portion of units—specifically 5 percent of the residential dwellings, or up to 50 dwellings, whichever cap applies in the guidance—exceed the applicable clearance levels. If the sampled units all meet clearance within that tolerance, the building is considered to have achieved clearance.

This approach balances practicality with reliability: it avoids the impracticality of testing every unit while still providing strong assurance that the overall building is safe. It’s not correct to require sampling every unit, or to say clearance levels aren’t required, and clearance sampling isn’t restricted to interior dust samples alone; surface dust from pertinent areas (like floors and window sills) in the sampled units is typically used.