Draft screening levels asbestos, fiberglass, silica, Apr 2002

NYC 9/11 Public Portal Document

DRAFT COC Airborne Screening Levels April 1,2002 Asbestos - all types taken together Level Recommended actions Comments Air level: Evaluate the need to remove Screening value in air set at a level >0.01 fZcc * sensitive individuals from the where short term exposures 1 year) environment may result in exposures which contribute to Evaluate conditions in the area Settled Dust level: including representativeness of air Settled dust threshold is to protect to at > 100,000 frem^ samples, fibrous glass dust levels least a 1X10’'’ risk estimate for a one and loading. year exposure. Air concentrations estimated for different activities using Take actions to reduce exposures. a K factors based on Millette’s work - clean area on asbestos. Risk estimate is based on - resample estimates of air levels, and duration of - ongoing cleaning exposure for different activities. (100,000frcm2 corresponds to a 3x10- 5 risk for a one year exposure) Air level: Evaluate conditions in the area For those areas where air levels would NYC background including representativeness of air not warrant removal of sensitive - 0.01 free * samples, fibrous glass dust levels individuals, but are above the 0.001 and loading. free, continued cleaning and evaluation Or is prudent.

Settled Dust level: If air samples were not taken, then Settled dust threshold is to protect to at appropriate air sampling should be least a 1X10"'’ risk estimate for a 30 10,000 frem^ conducted to determine if fiber year exposure. Air concentrations To levels are elevated. estimated for different activities using 100,000 frem^ a K factors based on Millette’s work Take actions to reduce exposures. on asbestos. Risk estimate is based on - clean area estimates of air levels, and duration of - resample exposure for different activities. - ongoing cleaning (10,000frcm2 corresponds to a 1x10-4 risk for a 30 year exposure)

Air level: No action required

^NYC background

And

Settled Dust level: backgroimd or 1000 frem^

* Fibers with length > 5/zm with an aspect ratio 3:1, as defined in the ACGIH TLV.

NYC-WTC_000164460