NYC-WTC_000208755

NYC 9/11 Public Portal Document

Liberty Mutual.

Industrial Hygiene Air Sample Results Summary for Week of 01/18/02-01/25/02

OSHA 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 which are established by the American Conference ofGovernmental Industrial Hygienists, a private professional organization.

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

Shift Adjusted OEL - The OEL reduced to compensate for the reduced recovery time and longer exposure time posed by a 7 day per week, 12 hour shift work schedule.

Highest % of Shift Adjusted OEL - This is the percentage of shift adjusted OEL that the highest result represents.

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

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

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

Walter E. Frank, CIH,CSP Senior Industrial Hygienist Liberty Mutual Group

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NYC-WTC_000208756