EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

and may cause throat and lung irritation. Because of the energy released by the WTC disaster, dust containing particulate matter in this size range was generated. If this dust had not been able to settle, or if there had remained a continuous source of particulates being released into the ambient air, then there would have been a concern that hazardous dust could infiltrate nearby homes and offices. However, ambient monitoring for fine particulate matter in the WTC area has shown that, since late October, the levels of PM 10 (inhalable dust fraction 10 microns and smaller) and PM 2.5 (respirable fraction 2.5 microns and smaller) have been below the levels of concern: PMIO 150 ug/m3 NAAQS 24-hour average PM2.5 65 ug/m3 NAAQS 24-hour average 40 ug/m3 Air Quality Index, 24-hour average (moderate impact)

This indicates that there is no continuing concern of hazardous fine particulate matter entering homes and offices in the WTC area. Therefore, particulate matter will not be monitored in any further indoor environment testing.

Refractory Ceramic Fibers (RCF)

Ceramic fibers are reasonably anticipated to be human carcinogens based on sufficient evidence of carcinogenicity in experimental animals [lARC V.43, 1988]. When administered by inhalation, rats of both sexes showed a significant increase in the incidence of benign and malignant tumors of the lung. However, there are no data available to evaluate the carcinogenicity of ceramic fibers in humans [lARC V.43, 1988].

It is not expected that ceramic fiber-containing materials were present in large quantities in the WTC buildings, since those materials are used mainly in industrial high temperature applications.

Some air sampling has been performed for ceramic fibers in a recently completed study by ATSDR and NYCDOH [NYCDOH, 2002]. During the period from November 4 through December 11, 2001, environmental samples were collected in 30 buildings in lower Manhattan and four locations above 59* Street. Settled dust samples were taken both indoors and out, and analyzed for asbestos and other fibers by PLM. Although fibrous glass was reported in many settled dust samples, RCF was not reported as a fiber present by PLM. Air samples, also taken in these areas, were analyzed for fibers by PCM. Six of these study area air samples appeared to contain fiber levels in air higher than the levels found above 59* Street. Four of the samples from areas containing fibrous glass in settled dust were re-analyzed by SEM and were not found to contain any ceramic fibers above the detection limit (0.00004 free).

Even though this is a limited study, it appears to confirm limited to no use of ceramic fibers in the WTC buildings. Therefore, ceramic fibers will not be monitored in any further indoor environment testing.

Mold

3

NYC-WTC_000145990