WTC environmental health assessment draft, May 2002

NYC 9/11 Public Portal Document

Insulation Wools: Glass wool, rock wool and slag wool

Tier Action Insulation Wools (settled dust) Insulation Wools (indoor air)

Level Basis Level Basis

I Aggressive cleaning. > 100,000 Millette’s K >0.1 f/cc ACGIH TLV of If levels persist, take f7cm’ factor to estimate 1 f/cc (see additional action to airborne levels for narrative below). reduce exposure. different activities (see narrative Evaluate conditions in below); the area including representativeness of air samples, fibrous glass dust levels and loading.

U Maintain 100,000 0.01 to 0.1 recommended f/cm^ to f/cc cleaning methods. background Consider additional montoring.

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

ni No further action background Level is set at that < 0.01 f/cc ACGIH TLV of required found in 1 f/cc (see background, or nanative below) unaffected, areas. In this way, no increase in risk due to the fibers would be fexpected. * Fibers with length > 5wm with an aspect ratio 2 3:1, as defined in the ACGIH TLV. Air concentrations measured by PCM, NIOSH 7400, confirmed by SEM.

The Tier I level for insulation wools in settled dust was based on Millette’s (full name & reference?) K factors, which are empirical relationships between concentrations of asbestos fibers in settled dust and indoor air. Millette developed the K factors by studying matched air and dust samples taken from various homes, at varying levels of activity in the home. The Tier I

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CONFIDENTIAL CITY_21MC100_003423801 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

NYC-WTC_000176172