Asbestos air and dust test results, BMCC, Feb 2002

NYC 9/11 Public Portal Document

B.M.C.C. Page 4 Dust & VOC Levels December 6, 2001 The outdoor readings indicate that the dust levels vary outdoors. An increase in outdoor levels appears to correspond to an increase in indoor levels in the portable trailers. The higher efficiency filters for the large central air handling units (AHUs) for the Main Building, based on these December 4th readings as. well as the November 13th & November 20th readings, are keeping dust levels significantly lower indoors. The grade of filters for the smaller units in the portable trailers are not as efficient in filtering the outdoor air.

Using portable HEPA-filtered air cleaners in the trailers markedly reduced the dust levels, as seen in the December 5th readings.

TBE recommends using portable. HEPA-filtered air cleaners in all of the classroom trailers. In addition, windows and doors of the portable trailers should be kept closed as much as possible.

VOCs Air Sampling

On December 4, 2001, TBE used a direct reading, portable Photo Ionization Detector (PID) to: (1) compare levels of VOCs in various areas of the Main Building, the Portable Trailers, and outdoors, and, (2) to attempt to locate a possible point source(s) of VOCs that may be affecting the indoor air quality of the spaces.

The Mini-RAE PID is used for the measurement of most VOCs, down to a level of 0.1 ppm (part per million). The sensor consists of a sealed UV light source that emits photons which are energetic enough to ionize many trace species (particularly organics) but do not ionize the major components of air such as oxygen, nitrogen, carbon dioxide, carbon monoxide, or water. The field created on an electrode will drive any ions formed by adsorption of the UV light to the collector electrode where the current (proportional to concentration) is measured. Response time for this direct reading instrument is under 5 seconds.

TBE found that readings on December 4th were lower than the readings collected on November 13th and similar to the November 20th data, in both the Main Building and the portable trailers. All indoor readings in the Main Building were 0.0 ppm [non-detectable] for VOCs. The outdoor readings were also 0.0 ppm. Most portable trailers showed some detectable levels, with a range of readings from 0.1 to 1.5 ppm; most of the readings were below 1.0 ppm. The morning readings were lower than the afternoon readings. For example, W-103 had a morning reading of 0.2 ppm and an afternoon reading of 1.5 ppm.

All of the indoor readings in the Main Building were non-detectable (0.0 ppm). The portable trailers mostly had readings below 1.0 ppm. TBE, in past indoor air surveys in other buildings, has detected indoor levels of VOCs using the PID in the range of 0.2-

NYC-WTC 000106367