WTC environmental health assessment draft, May 2002

NYC 9/11 Public Portal Document

measurements of ambient air around the WTC work zone have been significantly below EPA’s screening level (730 nanograms per cubic meter). This indicates that PCBs in ambient air are not considered harmful. Therefore, it is recommended that PCBs not be monitored in any indoor testing.

Chromium

Chromium is a naturally occurring element commonly used in metal alloys and plumbing coatings in high rise buildings such as the WTC. Chromium and its compounds can be found in air as very fine dust particles that eventually settle over land, and can cause cancer and other health problems if inhaled at high concentrations. To date, levels of chromium measured in ambient air around the WTC work zone have all been below EPA’s screening level of 0.6 micrograms per cubic meter (ug/m^). Because of these low values, chromium is not being considered a hazard at the WTC. Therefore, it is recommended that chromium not be monitored in any indoor testing.

Cadmium and Manganese

Cadmium and Manganese, both hazardous air pollutants, were detected in some ambient air samples taken at the WTC site. However, cadmium was detected in only one sample at a level equal to EPA’s screening level of 0.2 ug/m^. Manganese was found in only three samples that were above EPA’s screening level of 0.5 ug/m’. Because of the low ambient concentration of these two metals, it is recommended that they not be monitored in any indoor testing.

Mercury

In early January 2002, it was reported that New York City Port Authority police officers were tested with high levels of mercury in their blood. This raised concerns over the air quality at the WTC area. It was later learned that the probable cause of the high mercury levels was canned tuna fish that the officers had eaten the day before the blood tests were done, and not WTC air. In fact, mercury has not been detected in any air samples taken to date in the WTC area.

In addition, data from a U.S. Geological Survey leachability study performed on both indoor and outdoor WTC dust samples found mercury in leachate samples only at trace levels (up to 18 parts per trillion [ppt] for outdoor dust and 130 ppt in indoor dust). Because only trace levels of mercury appear to be present in indoor dust samples, the probability that harmful levels could ever be released to the air is very low. Therefore, it is recommended that mercury not be monitored in any further indoor testing.

Particulate Matter

[What follows seems rather dismissive of PM, without a full explanation. The standard referenced for PM 10 is the hourly standard. Was the annual standard or 50 ug/m^ exceeded (or

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CONFIDENTIAL, CITY_21MC100_003423809 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

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