WTC environmental health assessment draft, May 2002

NYC 9/11 Public Portal Document

Asbestos

Tier Action Asbestos (Settled Dust) Asbestos (indoor air)

Level Basis Level Basis

I Aggressive > 30,000 Millette’s K >0.01 f/cc * 0.01 f/cc represents cleaning. If levels f/cm-' factor to estimate alX10-*risk persist, take airborne levels for >0.0004 f/cc estimate for a 1 additional action to >100,000 different activities year exposure reduce exposure. f/cm2 (see narrative below). Risk^based Evaluate scrcciiin^'levek for conditions in the Risk-based short term area, including scrccmri^ level for exposures^ 1 representativeness residential setting yr) may result in of air samples, (E-04 X 1 yr) cxposurc'y'^vhTch asbestos dust contribute to long” levels, and loading. term risk.

U Maintain 30,000 bfiff/cc 0.0004 f/cc recommended f/cn? to 0.0004 f/cc represents a 1X10“* cleaning methods. background Risk- based (or........... risk estimate for a Consider screening level for background) 30 year exposure. additional 10,000 to residential setting monitoring. 100,000 (E-04 X 30 yr). N¥€ backgTOUTld -teveHor Evaluate to 0.0004 residential setting conditions in the (E-04 X 30 yr). area including representativeness of air samples, fibrous glass dust levels and loading.

ni No further action < or - Level is set at that 0.0004 f/cc Level is set at that required. background found in (of found in or 1000 background, or background) background, or unaffected, areas. unaffected, areas. In this way, no <01--NYC In this way, no increase in risk bdckground increase in risk due due to the fibers to the fibers would would be be expected. expected. * f/cc = fibers (greater than 5 micrometers long) per cubic centimeter of air. Air concentrations measured by PCM, NIOSH 7402, confirmed by TEMJ Notcrthat-ftb id stiucturcs iro used in this rcpoiX.

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CONFIDENTIAL, CITY_21MC100_003423798 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

NYC-WTC_000176169