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 = ==

ALAR DEP Air, Noise and Hazardous Materials

· Wastewater Treatment Air Monitoring in Lower Manhattan ROHREMar DEP monitored the ambient outdoor air for asbestos following the World Trade & ALE Monitoring Center (WTC) disaster. This effort augmented ambient air asbestos sampling performed by the EPA and other state and city agencies. There is currently no outdoor ambient standard for asbestos. The US and NYC standard for asbestos in community and residential buildings is 0.01 fibers/cubic centimeter (f/cc) in Ruk indoor air. An indoor area which has had asbestos detected and then removed must show that air samples are at or below the 0.01 f/cc standard before the indoor area Forme can be re-occupied. Although the ambient outdoor air was monitored, DEP used the indoor air standard as a way to characterize the levels of asbestos in the air. Accountability Bureaus Since the measurement protocol used, phase contrast microscopy (PCM), counts Jobs fibers, DEP also conducted an additional analysis for all samples that were above 0.01 f/cc. This measurement protocol is called transmission electron microscopy (TEM) and counts the number of asbestos fibers in the sample. EPA reported their data in TEMs, and provides a good explanation of the interpretation of the standard that uses this methodology on their website.

Inioimagen EPA has also recently published the results of two studies related to the WTC DER NAWS disaster: The Toxicological Effects of Fine Particulate Matter Derived from the Destruction of the World Trade Center, and The Exposure and Human Health ContactUD Evaluation of Airborne Pollution from the World Trade Center Disaster. To read both reports, please click here.

Results indicate that, as expected, asbestos was present in some of the debris at the site and in areas very close to the site. Between September 28, 2001 and August 3, 2002, the vast majority of air sampling results outside the security zone were below the standards for asbestos in indoor air.

To view the 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 19 Vesey and LEO JAY ST O NAR and Worth Street West Street W D TH ORT ST G EN UVER SP 2 Broadway and 20 Vesey OM H DU AS S O Worth Street between LS. CH AN ST DA AM RE G Church and BE AD ST WA RS S E S Greenwich RD T T

http://www.nyc.gov/html/dep/html/airmonit.html 8/13/2003

NYC-WTC 000148557