NYC-WTC_000206884

NYC 9/11 Public Portal Document

^liberty " Mutual.

Industrial Hygiene Air Sample Results Summary for Weeks of 11/25 and 12/2

3 Highest Analyte - The analyte found in the hipest concentration with respect to its occupational exposure limit.

Highest Result - The concentration of the highest analyte.

OSH A PEL - This is the Permissible Exposure Limit (PEL) for the highest analyte. PELs are established by an OSHA rule-making process and are the legal occupational exposure standards.

ACGIH TLV - This is the Threshold Limit Value (TLV) for the highest analyte. TLVs are voluntary guidelines for occupational exposure wliich are established by die American Conference of Governmental Industrial Hygienists, a private professional organization.

Highest Result / % of OEL - This is the percentage of the occupational exposure limit (OEL) that the highest result represents. This is the value in the “Highest Result” column divided by the lower of either the PEL or TLV and converted to a percentage.

#of NQs - This is the number of analyses that reported that concentration as “not quantifiable” (NQ).

% off NQ - This is the percent of the total analyses which were reported as “not quantifiable”.

Ifyou have any questions concerning this information or would like fiirther details about these results, feel fi-ee to contact the Liberty Mutual Industrial Hygienist on duty @ 917-566-2576.

Mike Ramsey, CSP, CIH Senior Industrial Hygienist Liberty Mutual Insurance Group

12/20/01

CITY_21MC100_006712816

NYC-WTC_000206885