Air quality monitoring report for NYU Downtown Hospital, Sep 2001

NYC 9/11 Public Portal Document

Asbestos — Airborne asbestos has a PEL of 0.1 fibers per cubic (0.1 f/cc). A separate clearance criteria of 0.01 f/cc is centimeter of air used subsequent to an asbestos abatement project, as a margin of safety. PEL is typically fiber count, which counts all fibers, not just the asbestos in the measured as a total. When total counts are elevated, confirmatory additional analysis can be performed to determine if any of the fibers were actually asbestos, and the true asbestos flcc can then be determined.

The USEPA considers asbestos levels below 0.005 f/cc to be acceptable for occupancy of schools, and general outdoor air. They also use a clearance level of 70 asbestos structures per square millimeter (70 as/mm2) of air sampling filter if the air sample was at least 1,199 liters in volume.

Bulk materials are considered to be non-asbestos by the USEPA when less than 1% asbestos in volume. As with the above air sampling, further confirmatory analysis can be performed when warranted.

Dust The PEL for airborne dust is 15 milligrams per cubic meter of — air (15

Carbon dioxide — The PEL for carbon dioxide (CO2) is 5,000 parts per million (5,000 ppm). The outside air in your area typically has a concentration of 340 to 470 ppm. Indoor air levels above 1,000 ppm are typically considered to be indicative of a need for more fresh air intake.

Confidential - Page 5 of 5

NYC-WTC 000104678