VOC air sampling report for World Trade Center site, Sep

NYC 9/11 Public Portal Document

concentrations were not as high (in absolute terms or relative to toluene and xylene) as most of the EPA sampling results.

2. At 75 Park Place (upwind of the WTC site) and at 225 Rector (cross-wind), VOC levels, except ethanol, were in the range of levels commonly found in outdoor air samples (backgroimd). At 140 Broadway (downwind), where the smoke plume from the WTC site . was visible during each of the sampling events, most of the VOCs were greater than background (generally less than five times background levels and all (except trichlorofluoromethane) less than about ten times background levels).

3, Generally, VOC concentrations at 140 Broadway were about 3 times greater than those at Park Place and Rector Place sites.

4. During each of the sampling events, the smoke nlume was visibly evident at 140 Broadway and fire odors were noticeable at the street level. During sampling at the other sites, the smoke plume was not visibly evident at the sites. WTC-related odors were sometimes noticed at the Rector Place site and not noticed at the Park Place site.

5. VOC concentrations on the roofs were not substantially different from street-level VOC concentrations at each of the sampling sites, including 140 Broadway (53 stories high).

6. Concentrations of VOCs associated with the smoke plume were about 20 times greater in the grab sample at the pile than at 140 Broadway.

7. High levels of trichlorofluoromethane (a refrigerant, R-11), were observed in the samples from the roof at 140 Broadway. The building manager said that a chiller leak sensor had detected a minor refrigerant leak of R-11 on Friday (Sept 28) morning. The problem was corrected later in the day. The chiller is located on the 52"^ floor and a mechanical room vent was about three meters (10 feet) from the sampler.

8. Elevated methylene chloride concentrations were also detected on the roof of 140 Broadway with slightly higher levels found in the afternoon sample when the chiller was being repaired. Methylene chloride is commonly used as a degreaser in building HVAC system maintenance and repair work. It was not measureable in the plume sample or any of the other samples.

9, The field forms for the morning samples for 140 Broadway (roof and street level) were switched so the laboratory report forms misidentify the roof and street level samples at this location.

10. Because the trichlorofluoromethane and methylene chloride were on the roof top and people are not being directly exposed to them, they are not discussed in the health implications section.

11. Assuming that the fires and smoke will continue to diminish as the recovery work progresses, these data suggest that additional VOCs sampling for these compounds is not necessary.

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