NYC-WTC_000220337

NYC 9/11 Public Portal Document

Rjpspirable Silica: The overwhelming majority of 861 silica samples (excluding Wk and blank samples) show no detectable levels of airborne silica. However, 54 expoeures exceeded the PEL. The highest sample result was a.pprcxiina«Iy twentyone times the OSHA limit (jack hammwing concrete 16 feet below srade). The other elevated exposures were approximately one to founeen liines the OSHA limit. These expoeures ownrred during: 1) pre-drilling /slurry wall 2) jack hammering, 3) nibble removal and loading operations near the Winter Garden; 4) dining the breaking up of concrete in the pit; 5) while dri)l«g the concrete slurry wall, 6) flagging operations in pit, and 7) while chipping concrete with power tools during demolition activities at 7 WTC’s parking garage. Most of the work areas where apparent overexposurcs lo silica occurred were in the rubble pile/pit; an area where OSHA cwtinuee to eocomage th* use of respiratory protection. Organic Compounds: OSHA has taken a total of 652 samples (excluding bulk and blank samples) for organic compounds such as acetaldehyde, acrolein, acrylomlrilc, benzene, 2-butanone, carbofurans, dioxin, PCBs, ethyl benaene, formaliehyde. Freon R’22 (chlorodiflourometbane), hexone, isocyanates (e.g. MVI top, perchloroethylene, polynuclear aromatics, phosgene, styrene, toluane, 1-3 butadiene, trichloroethylene, vinyl chloride, glutaraldehyde, and xylene. Screening samples initially showed elevated levels of some organic chemicals resulting H om the fires bumins in the rubble pile, SubsequcY personal and area sooiple* show worker exposure levels to be below OSHA limits. However, one personal sample result for a benzene sample taken was found to be at the 8-hr, OSHA Allowable Limit concentration of 1 ppm. This was found on a backhoe operator moving debris on 10/7/01. See informiion below fur the specific counts in regards to polynuclear aromatics, Frvon R-22, phosgene and dioxin.

Dioxins: OSHA has taken 10 dioxin samples (excluding blanks) in thcplunic over hot spots in (and around the perimeter of) the nibble pile, Dioxir levels detected

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NYC-WTC_000220338