Air monitoring inspection report for 310 Greenwich Street, Oct 2001

NYC 9/11 Public Portal Document

TRANSMISSION ELECTRON MICROSCOPY (TEM) METHODOLOGY

Microscopy (TEM) is a technique, which focuses an electron beam Transmission Electron the beam microscope column (under a vacuum). As onto a thin sample mounted in the the sample is through the sample, an image resulting from varying density of either transmits for TEM analysis can be collected on fluorescent screen. Air samples projected onto a direct transfer polycarbonate filters and are prepared using mixed cellulose ester or a carbon- Direct preparation allows for the transfer of techniques (as per EPA regulations). on to a of the filter material (with embedded fibers and particulates, etc.) right coated replica intermediate Indirect transfer techniques require an copper grid suitable for TEM analysis. resulting in an increased fiber amount. step that may break-up fiber bundles, sis of air es by on preparation Several methods exist for the a nd nonlymandatory TEM ml ethods set forrth microscopy. Most significant are the mandatory be 40 CFR 763, Subpart E (AHERA Regulations). These methods are to as appendices to projects. for analysis of final clearance air samples on school abatement used airborne asbestos concentration The analytical sensitivity is the determined by airyvolume collected and the counted under.the electron microscope. It is sensitivity be no the filter examined. This method requires that the analytical proportion of greater than 0.005 structures/cc. register but pumps must be calibrated and their low indicators Sampling removing the cap for field blanks are to be taken by no more than 10 liters/min. Two (2) sample set. +is than 30 seconds. A sealed blank is to e crried with each hthe more IedaThese samples are submitted to representative cassette is not to be opened in thef a The hould be laboratory for quality control purposes. liters of a'►rSThesamples a re e ate~ b opght to a time to conform at least a volume of 1200 certified laboratory for the analysis.

NYC-WTC 000109437