NYC-WTC_000199886

NYC 9/11 Public Portal Document

consistent with either or both of those operations as the potential source of the trace levels detected. None of the target hydrocarbons, including volatile organic compounds such as benzene, were not detected in any of 8 air samples collected from inside or outside the school on December 9 or 11, 2001.

Volatile Organic Compounds plus Library Search (December 15,2001)

Five air samples were collected for analysis of volatile organic compounds with a 15- compound forward library search (VOC+15) on December 15, 2001. Sampling locations included three outdoor samples (main entrance, roof, and the rear playground) and two indoor samples (cafeteria and second floor hallway). A few targeted VOCs were detected at trace levels both outside and inside the school, including benzene (maximum 0.9 ppb outside, 0.8 ppb inside), ethylbenzene (0.3 ppb outside, 1.0 ppb inside), toluene (1.6 ppb outside, 2.8 ppb inside), and xylenes (1.5 ppb outside, 4.7 ppb inside). In addition, several non-target VOC compounds were detected both inside and outside of the school. Overall, the type and levels of VOCs detected are generally consistent with urban background concentrations documented by USEPA.

Particulates and Other Air Quality Parameters (December 8 to 14,2001)

Levels of carbon dioxide, carbon monoxide, and relative humidity were within guideline ranges. Levels of particulates (PM2.5) varied significantly during the period. Based on periodic measurements taken at several locations inside and outside of the school, the average particulate levels on all five days (indoor averages ranged from 22 to 36 ug/m’) were below the threshold level of 40 ug/m^ used by USEPA for sensitive receptors inside the school, although some instantaneous particulate measurements were higher, up to 68 ug/m^, which is slightly above the 65 ug/m^ guideline used by USEPA for normal populations. It should be noted that the 40 ug/m’ and 65 ug/m’ limits are established for outdoor conditions as an average concentration over 24 hours. Outdoor levels were approximately similar to indoor readings on December 8 and 9, but outdoor readings were higher than indoor readings on December 10 and 12, with average outdoor readings of 51 ug/nL on December 10 and 52 ug/m"' on December 12. In addition to the periodic particulate monitoring conducted, three locations were monitored continuously for approximately 24 hours during this period. One indoor location, the cafeteria, had average particulate levels of 30 ug/m^ on December 8-9, 44 ug/m^ on December 11-12, and 58 ug/m^ on December. Outdoor levels were somewhat higher, with average levels on the roof exceeding 65 ug/m^ during December 12-13 and 13-14, and outside the main entrance on December 12-13. These measurements were made with the school ventilation system shut down while improved filtration systems were installed. Further assessment of particulate levels is warranted with the upgraded ventilation systems operating. As previously discussed, an evaluation of the testing method being used for particulates is also underway, along with further particulate monitoring to assess current air quality. In general, particulate levels in the area of the school, including at a measurement station at the Borough of Manhattan Community College, have been well below 40 ug/m^ on most days in recent weeks.

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