WTC environmental health assessment draft, May 2002

NYC 9/11 Public Portal Document

Refractory Ceramic Fibers (RCF)

Tier Action RCF (settled dust) RCF (indoor air)

Level Basis Level Basis

I Aggressive > 10,000 Millette’s K factor >0.01 f/cc ACGIH TLV of cleaning. If levels f/cm^ to estimate airborne 0.2 f/cc (see persist, take levels for different narrative below) additional action activities (see to reduce narrative below).’ exposure.

Evaluate conditions in the area including representativeness of air samples, fibrous glass dust levels and loading.

n Maintain 10,000 0.01 f/cc to recommended Fcm4o background cleaning methods. background Consider additional montoring.

Evaluate conditions in the area including representativeness of air samples, fibrous glass dust levels and loading.

m No further action Background Level is set at that •Background Level is set at that required. found in found in background, or background, or unaffected, areas. unaffected, areas.' In this way, no In this way, no increase in risk due increase in risk due to the fibers would to the fibers would be expected. be expected. * Fibers with length > 5urn with an aspect ratio > 3:1, as defined in the ACGIH TLV. Air concentrations measured by PCM, NIOSH 7400, confirmed by SEM;

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CONFIDENTIAL, CITY_21MC100_003423803 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

NYC-WTC_000176174