Residential sampling protocol, World Trade Center, Oct 2001

NYC 9/11 Public Portal Document

me residential plan octi S.wpd

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1. No restrictions on access to any area Respirable silica defined as silica less than 4 pm. Air Settled dust action level set as close to 1/10 NIOSH REL as > 5% crystalline 2. Evaluate dust loading and silica content to practical based on sampling methods (NIOSH 7500). silica determine if dust cleanup is warranted I Activity level, as well as dust content and loading, will Air 3. Air monitor under high activity' conditions to influence air levels of silica. If air sampling was under < 6 pg/m’ determine if there is a potential for elevated silica in aggressive conditions, this represents worse case and air due to dust content the area can be cleared. I Settled dust No further actions Respirable silica defined as silica less than 4 pm. Air < 5% respirable action level set as close to 1/10 NIOSH REL as siUca practical based on sampling methods (NIOSH 7500).

Air < 6 pg/m’ I

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