Re-occupancy recommendations for 170 Broadway, Sep 2001

NYC 9/11 Public Portal Document FEB-25-2002 18:04 HYGIENETICS NYC 212 244 8505 P.08/21

N gg~leneticsw nyironmental Hygienetics Environinental Servie s, Inc. I West 34th Street Phone: (212) 244-3443 7th Floor Fax- (212) 244-8505 Ncw York, NY 10001

September 27, 2001

Ms. Peggy Nash Building Manager Jones Lang LaSalle Management 170 Broadway Now York, NY 10038

Re: Report of Ambient Air Sampling Results 170 Broadway, New York, NY -

Dear Ms. Nash:

Hygienetics Environmental Services, Inc. (Hygienetics) conducted ambient air sampling throughout the tenant spaces and common areas at the above-captioned facility. This air sampling was conducted subsequent to the interior spaces undergoing environmental cleaning by Pinnacle Environmental Corp. during the period September 19 - 23, 2001.

Pinnacle utilized NYC and NYS Certified asbestos handlers to perform all aspects of the environmental cleaning that was executed at 170 Broadway. Work procedures included the use of HEPA vacuums, and wet wiping techniques.

Air monitoring was performed by setting up a sampling train at each sampling location. Each train consisted of a high volume air sampling pump, which was calibrated to collect air in accordance with the appropriate sampling methodology (NIOSH 740() Method for airborne fibers), attached to 0.45 micrometer pore size, 25 millimeter diameter mixed cellulose ester membrane filter cassettes with tygon tubing. Open faced cassettes were utilized for the air sampling.

Area air samples were collected at representative interior spaces on each of the floors at 170 Broadway. In addition, field blank samples were also submitted to the analytical laboratory, for quality control/quality assurance (QA/QC) purposes. All air samples were submitted for analysis by 5rientiflc Laboratories, Inc. a New York State Department of Health (FLAP) Approved laboratory.

On-site pump calibration was performed with a high-flow rotameter, at the start and completion of each sample collection period, to ensure an accurate volumetric reading_ The rotameter's calibration was confirmed prior to its use on-site, utilizing a Mini Buck Model M-30 bubble calibrator, a primary calibration standard.

NYC-WTC 000105740