Air Monitoring in Lower Manhattan
DEP monitored the ambient outdoor air for asbestos following the World Trade 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 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 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.
Since the measurement protocol used, phase contrast microscopy (PCM), counts 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.
EPA has also recently published the results of two studies related to the WTC disaster: The Toxicological Effects of Fine Particulate Matter Derived from the Destruction of the World Trade Center, and The Exposure and Human Health 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 on the map or table below. (Links will open in a new browser window)
* NOTE: This data was inadvertently omitted from the original posting. It was subsequently posted on 11/20/06.
School Monitoring Data
DEP worked with the involved City agencies, including the Board of Education, to provide air monitoring in and around the schools near the World Trade Center disaster site. DEP collected 8 hour ambient air samples that were analyzed for asbestos at four locations. These locations were outside of the main entrances to: Stuyvesant High School, IS/PS 89, PS 234 and the High School of Economics and Finance. DEP began sampling on October 4, 2001, and completed sampling on June 30, 2002. From October 4th through October 18th, DEP only did a TEM analysis if the PCM concentration was above 0.01 fibers per cubic centimeter (f/cc). During this period of time, there was only one reading above 0.01 f/cc. The TEM result was below the Asbestos Hazard Emergency Response Act (AHERA) standard of 70 structures per square millimeter (s/sqmm). As of October 19, 2002, DEP began conducting a TEM analysis on all samples to provide a direct comparison to the AHERA standard. Between October 19 and June 30, 2002, all samples were well below the AHERA standard of 70 s/sqmm.
School Monitoring Data
Last updated May 4, 2007