NYC-WTC_000199582

NYC 9/11 Public Portal Document

Chemical Reason Benzene Benzene is very volatile and dissipates into ambient air quickly. Grab samples that recorded high (above the OSHA PEL of 1 ppm) concentrations on the debris pile consistently dropped to below detection limits (20 ppb) at the site perimeter. PCBs In over 500 ambient air samples taken around the WTC work zone, none exceeded EPA’s screening level of concern for ambient air (see Appendix B). Chromium All measurements (over 300 samples) of chromium in ambient air around the WTC work zone have been below EPA’s screening level of concern for the ambient air (see Appendix B). Measurements in settled dust have been below EPA Removal Action Guidelines [EPA, 1997]. Cadmium Cadmium was found in only two out of 300 air samples at levels greater than EPA’s screening level for ambient air (Appendix B). Measurements in settled dust have been below EPA Removal Action Guidelines [EPA, 1997]. Manganese Manganese was found in only four of over 300 air samples at levels that were greater than EPA’s screening level for ambient air (Appendix B). Measurements in settled dust have been below EPA Removal Action Guidelines [EPA, 1997]. Mercury Concern regarding mercuiy has been raised by a report of slightly elevated blood mercury levels in four Port Authority Police Officers at the WTC site (69 were screened). A NYC Department of Design and Construction report [Rottner, 2002] concluded that air and bulk data have not shown elevated Hg levels. The report also noted that routine urine screening of NYC firefighters assigned to the site did not indicate any sign of Hg exposure. A U.S. Geological Survey leachability study [USGS 2001] of indoor and outdoor WTC settled dust samples showed that it is unlikely that harmful levels of mercury could ever be released to the air. In addition, indoor air sampling using a Lumex Analyzer at numerous residential dwellings close to Ground Zero determined mercury vapor concentrations to be well below EPA’s Reference Concentration (RfC) of .3 ug/m’ [Johnson, 2002]. Particulate Ambient monitoring in the WTC area has shown that, since late October, levels Matter of PM 10 and PM 2.5 (two commonly measured inhalable PM sizes) have been (PM) below EPA’s level of concern for the ambient air (see Appendix B), indicating that there is no continuing source of PM entering homes and offices. EPA’s Environmental Data Trend Report World Trade Center, 9/11/01 - 4/24/02 [EPA, 2002a] concluded that PM 2.5 and PM 10 appear to have returned to levels of a steady background state.

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NYC-WTC_000199590