World Trade Center asbestos situation memorandum, December 2001

NYC 9/11 Public Portal Document

Table 4. RE-CALCULATION OF REGION 1 DUST BENCHMARKS USING MORE VALID VALUES

FORMULA USED BY REGION 1:

Benchmark for X K-Factor (K-Factor Air Level, structures per asbestos In Dust expressed as an milliliter (s/mL) (s/cm2) exponential)

45,000 X 0.000001 (10-®) 0.045 This Is the level derived from the This is the K-factor chosen by Region 1 for their This is the alleged background outdoor formula by Region 1 calculations, from the 2 highest ones from a total of six K- air level put Into the formula by Region 1 factors. A higher K-factor results in a calculation of a This value is the one highest higher, less protective dust level. The two K-factors with measurement found in an early 1983 10(-6) values were for a person cleaning out a storage study. For most of the measurements, room and fora person vacuum cleaning. asbestos was not even detectable.

1,000 X 0.00001 (10-®) 0.01 Dust level if detection limit of the early This is the K-factor more applicable to a school. This is the detection limit of the study 1983 study is used, and K-factors representing gym activities and a person sweeping floors cited. Most of the actual measure air more applicable to a school are used, with a broom levels were below this detection limit

100 X 0.000001 (10-®) 0.0001 Dust level if air concentration is urban This is STILL the inappropriate K-factor chosen by Region Outside ambient air level, urban areas. level cited by the CDCs ATSDR, but 1 for their calculations found credible by the CDC's ATSDR still using the inappropriate K-factor.

10 X 0.000001 ( 10-®) 0.00001 Dust level if air concentration is rural This is STILL the K-factor chosen by Region 1 for their Outside ambient air level, rural areas, level cited by the CDC's ATSDR, but calculations found credible by the CDC's ATSDR still using the inappropriate K-factor.

10 X 0.00001 (10-®) 0.0001 Dust level if K-factors more relevant This is the K-factor more applicable to a school. Outside ambient air level, urban air, to school used, and ATSDR value for representing gym activities and a person sweeping floors found by the CDC's ATSDR urban outdoor air used. with a broom

1 X 0.00001 (10-®) 0.00001 Dust level if K-factors more relevant This is the K-factor more applicable to a school. Outside ambient air level, rural areas, to school used, and ATSDR value for representing gym activities and a person sweeping floors found by the CDC's ATSDR rural outdoor air used. with a broom

1 X 0.0001 (10-*) 0.0001

Dust level if average of the six K- Average of six different K-factors in study, allowing Outside ambient air level, urban air, factors used, and ATSDR value for for a safety margin of enor found by the CDC’s ATSDR urban outdoor air used.

0.1 X 0.0001 (10^) 0.00001

Dust level If average of the six K- Average of six different K-factors in study, allowing Outside ambient air level, urban areas, factors used, and ATSDR value for for a safety margin of error found by the CDC's ATSDR rural outdoor air used.

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