What is the EPA clearance value for window sills?

What is the EPA clearance value for window sills?

• A. 40 ug/ft2
• B. 250 ug/ft2
• C. 400 ug/ft2
• D. 100 ug/ft2

Answer: (B)

Clearance values are the maximum allowed amounts of lead dust on a surface after abatement or renovation work, used to judge whether cleaning is sufficient. For interior window sills, the EPA sets 250 micrograms of lead per square foot as the allowable limit. This value comes from post-work dust clearance standards that vary by surface type because different surfaces accumulate dust differently and pose different cleaning challenges. The key idea is that if wipe samples from the sill show lead levels at or below 250 μg/ft², the area passes clearance; if a sample exceeds this, re-cleaning and repeat testing are required until all samples meet the limit. (Note: floors have a stricter limit of 40 μg/ft², and window troughs have a higher limit such as 400 μg/ft²; other numbers like 100 μg/ft² do not apply to window sills.)

Clearance values are the maximum allowed amounts of lead dust on a surface after abatement or renovation work, used to judge whether cleaning is sufficient. For interior window sills, the EPA sets 250 micrograms of lead per square foot as the allowable limit. This value comes from post-work dust clearance standards that vary by surface type because different surfaces accumulate dust differently and pose different cleaning challenges. The key idea is that if wipe samples from the sill show lead levels at or below 250 μg/ft², the area passes clearance; if a sample exceeds this, re-cleaning and repeat testing are required until all samples meet the limit. (Note: floors have a stricter limit of 40 μg/ft², and window troughs have a higher limit such as 400 μg/ft²; other numbers like 100 μg/ft² do not apply to window sills.)