Asbestos air and dust test results, BMCC, Feb 2002

NYC 9/11 Public Portal Document

B.M.C.C. Page 3 Dust & VOC Levels November 20, 2001 1 Readings on November 20th were collected over 2 different time periods, 10:05-11:05 am, and 1:35-2:34 pm. Readings were taken throughout the building. This includes classrooms, common areas, hallways, offices, gymnasium, etc. The outdoor readings, collected at various outdoor points, varied over a 2 minute sampling period, with peaks up to 46g/m3. (Readings were collected every second during the sampling). These higher peaks would dissipate over a 1 minute range, and most of the outdoor reading on November 20th were in the range of 10 to 20 pg/m3. The outdoor readings on November 20th were lower than the outdoor readings collected on November 13th. During the night of November 19th, there had been a rain storm, followed by a windy day on November 20th. This was in contrast to November 13th, which was a sunny, calm day. Clearly, the rain (and strong wind) had reduced the amount.of fine dust' particlesoutdoors.

None of the areas tested in the Main Building exceeded 40 pg/m3 at PM2.5. Two rounds of sampling were conducted, one in the morning and one in the afternoon. Most readings were in the range of 5 to 15 pg/m3. This was lower than the November 13th readings, which showed a slightly higher range of 10 to 20 pg/m3.

The Portable Trailers, located on West Street, showed higher readings as compared to the Main Building. One measurement from the afternoon, in W-103, was 63 pg/m3. This reading was collected during class while the instructor was writing with chalk, which may have partially caused the higher reading. Two other morning indoor readings ranged from 48 to 52 pg/m3, and were collected from W-108 and W-103, again while instructors were using the chalkboard. It appears that: (1) the outdoor levels were more directly impacting the portable trailers as compared to the Main Building, and (2) the use of chalk can cause a rise in the number of fine dust particles.

It should be noted that the higher readings were not duplicated on the second round of testing, except for W-103, which again had the use of chalk. All of the other areas, including W-108, were below 40 pg/m3 during the second round of testing. The EPA's Air Quality Index standard is averaged over a 24 hour day. TBE was collecting direct reading levels, at that point in time. The levels detected were not averaged over a 24 hour period.

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 November 20th readings as well as the November 13th 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.

NYC-WTC 000106355