Legal hold notice for WTC documents, undated

NYC 9/11 Public Portal Document

Air Monitoring in Lower Manhattan Page 1 of 3

THE CITY OF NEW YORK DEP DEPARTMENT OF ENVIRONMENTAL PROTECTION

About DEP Air, Noise and Hazardous Materials Supply Wastewater Treatment Ar Noise S& HazMat Air Monitoring in Lower Manhattan DEP is monitoring the ambient outdoor air for asbestos. This effort is School o Asbestos augmenting ambient air asbestos sampling being done by the EPA and other Data Firms state and city agencies. There is currently no outdoor ambient standard for Asbestos asbestos. The US and NYC standard for asbestos in community and residential Rules'S buildings is 0.01 fibers/cubic centimeter (f/cc) in indoor air. An indoor area which a. Asbestos has had asbestos detected and then removed must show that air samples are at or Forms below the 0.01 f/cc standard before the indoor area can be re-occupied. Although the Citywide Accountability ambient outdoor air is being monitored, DEP is using this value as a way to characterize the levels of asbestos in the air. Bureaus .comesinner's Since the measurement protocol used, phase contrast microscopy (PCM), counts fibers, DEP is also conducting an additional analysis for all samples that are above T.Customer 0.01 f/cc. This measurement protocol is called transmission electron microscopy Information (TEM) and counts the number of asbestos fibers in the sample. EPA is reporting their data in TEMs, and provides a good explanation of the interpretation of the standard " }Education that uses this methodology on their website. Information

DEP News Results indicate that, as expected, asbestos is present in some of the debris at the site and in areas very close to the site. Between September 28, 2001 and the present, the Contact Us vast majority of air sampling results outside the security zone have been below the standards for asbestos in indoor air.

As testing continues, there may be the possibility of occasional short-term increases in levels of asbestos in the air above the residential standard of 0.01 f/cc of air. When the measured level for the outdoor ambient air is above 0.01 f/cc, the samples will be analyzed to determine how many of the fibers are actually asbestos fibers.

To view recent air monitoring results, click on a sampling location below or on the map (Links will open in a new browser window)

Sampling Site Location 1 West. Broadway and 19 Vesey and Wortn Street West Street 2 Broadway and 20 Vesev between Worth Street Church and Greenwich Street 3 Duane Street and 20A Vesey and

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