NYC-WTC_000187710

NYC 9/11 Public Portal Document

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^liberty Mutual.

Industrial Hygiene Air Sample Results Summary for Week of 2/15/02 to 2/22/02

Analyte Class - This column includes general category of the agents (substances) which were sampled.

It of Samples - This indicates how many individual samples were collected for the agent class listed.

# of Analysis - This is the number of individual analyses performed. If only one analysis is performed on each sample, then the number of analytes will equal the number of samples. However, most samples ate analyzed for more than one agent as follows:

Metals: Aluminum, antimony, arsenic, barium, beryllium, cadmium, caldum, chromium, cobalt, copper, iron, lead, magnesium, manganese, nickel, selenium, silver, thallium, tin, titanium, vanadium, and zinc. Metal samples are sometimes also analyzed for total particulate.

Silica: Respitable dust, quartz, and cristobalite.

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

Sulfides: Hydrogen sulfide and sulfur dioxide

OEL - Occupational Exposure limit is the lower of the OSHA PEL or ACGM TLV. PELs are established by w OSHA rule-making process and ate die legal occupational exposure standards. TLVs ate voluntary guidelines for occupational exposure which ate established by the American Conference of Governmental Industrial Hygienists, a private ptofessional organization.

Highest % OEL - This is the percentage of the occupational exposure limit (OEL) that die highest result represents. This is the value in the “Highest Result” column divided by OEL 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 die 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.

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NYC-WTC_000187711