WTC environmental investigation report, Sep 2002

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page 30 of 56 gypsum, and portlandite, appear higher in some areas of lower Manhattan than in the comparison areas above S9th Street.

Approximate quartz levels in air ranged from 4 pg/m^-ig pg/m^J in the respirable fraction (PM4), 3 pg/m3-12 pg/m^J in the thoracic fraction (PMIO) and 3 pg/m3-13 pg/m^J in the inhalable fraction (PMIOO). Detection frequencies were similar in these fractions at 11%, 10%, and 14% respectively. However, quartz was only seen in one of the PM2.5 samples (3%) at an estimated 3 pg/m^J. Cristobalite, a different crystalline form of crystalline silica, was found in one lower Manhattan air sample at

15 pg/m^J in the PMIOO fraction. Cristobalite was not seen in any other sample, either air or settled surface dust. Across the size fractions, quartz was detected in air samples taken in lower Manhattan; it was not detected in the comparison areas above 59th Street. Therefore, the estimated airborne levels of quartz appear to be higher in some air samples from lower Manhattan than the chosen comparison areas above 59th Street.

Similar observations can be seen in the results for calcite and portlandite. Calcite and portlandite occur at a similar frequency to quartz (Table 11) and tend to be present in the same air samples (Appendix C.) Both minerals are present in PM4, PMIO, and PMIOO size fractions. Calcite was estimated at 3 pg/m^J-14 pg/m^J and portlandite at 14 pg/m^J-OS pg/m^J in inhalable dust. Mica and halite are not seen with the same frequency, but are detected in several air samples from lower Manhattan. Calcite, portlandite, mica, and halite are all detected in air samples taken in lower Manhattan, but not in air samples from the comparison areas above 59th Street (Table 11). Therefore, the airborne levels of calcite, portlandite, mica and halite appear to be higher in some air samples from lower Manhattan than in the samples from the comparison areas above 59th Street.

Gypsum was the most common mineral detected in air samples from lower Manhattan for all size fractions and was detected in 40 out of 114 respirable fraction (PM4) air samples at levels ranging from approximately 4 pg/m^J-lS pg/m^J. Gypsum was estimated at 3 pg/m^J-14 pg/m^J and detected less frequently in the PMIO (33 of 105) and PMIOO (24 of 101) size fractions, even though the detection limits for these fractions were lower. Gypsum was found in one of the PM2.5 samples, at approximately 3 pg/m^J. Across the size fractions, gypsum was detected in air samples taken in lower Manhattan at higher estimated levels than air samples taken from the comparison areas above 59th Street (up to 5 pg/m^J). Therefore, the airborne levels of gypsum seem to be higher in some air samples from lower Manhattan than the chosen comparison areas above 59th Street.

DISCUSSION

http://www.atsdr.cdc.gOv/asbestos/lowermanhattan/ResSamp_Sep2002_Text.html 07/18/2003 NYC-WTC_000178417