Indoor COCs benchmark levels discussion, March-April 2002

NYC 9/11 Public Portal Document

At ‘ +-------------------------------------------------- II I background or E-04 (30 I maintain recommended (i.e., I yr)/HQ =1 to E-04 (1 yr)/HQ 1 diligent wet/HEPA) cleaning 10 I methods - consider 1 additional monitoring ■+------------------------------------

III I < background or E-04 (30 1 no further action 1 yr)/HQ = 1 1 ----- +------------------------- +----------------------------------------

Asbestos (settled dust)

I I I Tier I Screening Value Action 1 I + I I I I > 10,000 fibers/cm2 | aggressive cleaning I I I (TEM AHERA counting rules) i (professional?) - if I I I I readings persist take 1 I I I additional action to reduce | I 1 I exposure | I ■+ +---------------------------- 1 I II I 1,000 (or background) I maintain recommended (i.e., | 1 1 10,000 f/cm2 I diligent wet/HEPA) cleaning | I 1 methods - consider I 1 I additional monitoring I ----- +-----------------------------+------------------ 1 III I < background or 1,000 f/cm2 | no further action I I (whichever is greater) 1 1 + + 1

Asbestos (indoor air)

___!___________ I ■+

I Tier | Screening Value 1 Action I '+ I I .028 f/cc (E-04 X 1 I aggressive cleaning | I I yr) I (professional?) - if 1 I I PCM/PCME measurement I readings persist take | I I 1 additional action to reduce I I I 1 exposure 1 I ,+---------------------------- 1 I II I .0004 (or background) I maintain recommended (i.e., 1 I I .028 f/cc 1 diligent wet/HEPA) cleaning I I i I methods - consider I I I additional monitoring I +---------------------- I III I < background or .0004 f/cc I no further action I I (whichever is greater) I I +----------------------

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NYC-WTC_000139417