NYC-WTC_000234895

NYC 9/11 Public Portal Document

Industrial Hygiene Air Sample Results Summary for Weeks of 12/21/01 to 01/04/02

Silica: Respirable dust, quartz, and cristobalite.

Aldehydes: Acetaldehyde, acrolein, benzaldehyde, formaldehyde, n-butyraldehyde, propionaldehyde, and valeraldehyde.

Acids: Hydrobromic acid, hydrochloric acid, hydrofluoric acid, nitric acid, phosphoric acid and sulfuric acid

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

Highest Result - Tlie concentration of the highest analyte.

OSHA PEL - This is the Permissible Exposure Limit (PEL) for die 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 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).

% 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 free to contact the Liberty Mutual Industrial Hygienist on duty @ 917-566-2576.

Donald A. Weber, Sr., IHIT Senior Industrial Hygienist Liberty Mutual Insurance Group

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NYC-WTC_000234896