Asbestos air and dust test results, BMCC, Feb 2002

NYC 9/11 Public Portal Document

TBE took realtime particle (aerosol) measurements in crg/m3 at 2.5 m diameters (PM2.5), using a TSI Model 8520 Dust Trak Aerosol Monitor. The Dust Trak is a laser photometer, which uses light scattering technology to determine mass concentration. The instrument has a sample flowrate of 1.7 Umin.

Based on the U.S. EPA's Air Quality Index, the level of concern for the general population from exposure to fine dust particles at PM2.5 is 65 ug/m3 averaged over a 24 hour period. EPA lowers the level of concern for sensitive groups, including children, the elderly, and people with heart or lung disease, to 40 ug/m3 averaged over a 24 hour period.

According to the EPA, when outdoor levels exceed 40 ug/m3 over a 24 hour period, people with respiratory disease, such as asthma, should limit outdoor exertion. Also, the EPA states, when outdoor levels exceed 65 ug/m3, all people, especially the elderly and children should limit prolonged outdoor exertion. The EPA Web site for particulate testing related to the World Trade Center disaster states "most healthy adults and children are expected to recover quickly from any symptoms of short-term exposure like coughing, wheezing, or eye and throat irritation. EPA expects the long-term risk from these short-term exposures to be low."

The EPA is collecting PM2.5 using gravimetric samplers, while TBE is using a laser particle counter (the TSI Dust Trak). According to TSI, some studies have shown that the Dust Trak sampled approximately 3 times more than the gravimetric samplers. This higher sampling efficiency may cause higher readings for the Dust Trak as compared to gravimetric samplers. 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.

Following is a summary table of PM2.5 particulate testing done on November 13th & 20th, and December 4 & 5: Date Outdoor Readings Indoor Rangel Comments ( g/M 3) m3 11/13 30-86 7-25 54 readings, [Main Building] none exceeded 65 .g/m3, none exceeded 40 m3 11/13 30-86 23-74 24 readings, [Portable Trailers] 1 exceeded 65 , .g/m3, 3 exceeded 40 m3 11/20 10-46 1-20 54 readings, [Main Building] none exceeded 65 ,,.g/m3, none exceeded 40 m3 11/20 10-46 8-63 25 readings, [Portable Trailers] none exceeded 65 .g/m3, 3 exceeded 40 ,g/m3

NYC-WTC 000106365