Document label for 10 Cortlandt Street

NYC 9/11 Public Portal Document

Hillrnann Environmental Group, if C

4.10 Dioxins

Dioxin refers to a group of chemicals created when many types of materials burn; it is also created during some types of manufacturing and incineration. Dioxin does not break down easily, remains in the environment and can be distributed by wind and water. It is found in a wide variety of places. People are exposed to dioxin primarily by eating meat, dairy and fish. The EPA has set a screening level based on an assumption of continuous exposure for a year to an average concentration of 0.16 nanograms (ng). This measurement is also known as a total Toxic Equivalency Factor (TEF). The TEF for the samples collected at selected locations throughout the building were below the EPA total TEF standard.

4.11 Fungal Spore Samples

Fungal spores are always present. They can be found in elevated numbers in residual dust that accumulates on the interior of ventilation ducts if exposed to elevated moisture. If found in excess amounts, these spores can produce allergy-like symptoms as well as asthmatic reactions in those who are sensitive to them. Hillmann recommends that the indoor levels do not significantly exceed the outdoor levels in either quantity or diversity. Based on the results, fungal concentrations were below comparable outdoor levels.

4.12 Airborne Asbestos (TEM)

Asbestos is a naturally occurring inincral. It differs from other minerals in its crystal development. The crystal formation of asbestos is in the form of long thin fibers. Over the years, asbestos has had many uses. Its primary use is as an insulator or fire retardant, but can also be used as a binder. Due to this versatility, asbestos can be found in many types of building materials. Even though the federal government placed a moratorium on the application of some asbestos products in the early 1970's, installation of these products continued through the late 1970's and even into the early 198(1's. EPA is using a protective standard under AHERA, the Asbestos Hazard Emergency Response Act, to evaluate the risk from asbestos in the outdoor and indoor air. This is a very stringent standard that is used to determine whether children may re-enter a school building after asbestos has been removed or abated. It is based on assumptions of long-term exposure. One quality control samples was taken and analyzed using transmission electron microscopy (TEM) for airborne asbestos on each floor. Results of these samples were lower than the New York City standard for occupancy of abated areas (less than 70 asbestos structures per square millimeter). Levels of airborne asbestos fibers ranged from 0.0041 fibers/cc to 0.0049 fibers/cc. The EPA "Clean Air" guideline, and the New York City criteria for reoccupancy following an abatement project is 0.01 fibers/cc. Observed levels were well below this limit.

22 Cortland: Street/New York. NY/project Number Y2-1458 Page 23

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