WTC environmental investigation report, Sep 2002

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page 6 of 56 information as possible with the sampling that could be conducted, given accessibility and equipment limitations.

Results from this investigation do not necessarily reflect conditions that would be found in other buildings, at other times just following the collapse, or after the sampling period. The measurements reflect conditions present at the time of the sampling (November 4-December 12, 2001) in the buildings and areas sampled. The limited number of results obtained from the comparison areas above 59th Street was an attempt to determine the New York City-specific background levels of asbestos, SVF, mineral components of concrete (quartz, calcite, and portlandite), and mineral components of building wallboard (gypsum, mica, and halite).

Sampling Overview

U.S. Public Health Service Commissioned Corps Readiness Force Officers were detailed to the New York City Department of Health and Mental Hygiene and composed the sampling teams for this investigation. The teams completed a survey form for each sampling location. The information collected by the survey was obtained from direct observations and from owners or representatives of building management when available. The survey form and photographs were reviewed along with the analytical results to put the sampling results into the context of where and how the samples were obtained and to determine the general conditions of the sampling locations.

Air and settled surface dust samples were collected and analyzed for the following materials used in WTC construction components: asbestos, SVF, crystalline silica, calcite, portlandite, gypsum, mica, and halite. SVF fe.g., fiberglass) is used in thousands of products because of its chemical resistance, strength, and ability to insulate against heat and sound. All of the crystalline minerals analyzed in this project are commonly used in building construction materials. Quartz, a form of crystalline silica, is a naturally occurring mineral and is a component of cement. Cristobalite andtridymite are different crystalline forms of silica. Calcite and portlandite are naturally occurring, high pH minerals used in cements and mortars. Gypsum is a naturally occurring mineral used in plaster, wallboard, and in some cements. Mica is a group of naturally occurring minerals that are used in paint, joint cements, plastics, roofing, and rubber. Halite (also known as rock salt or sodium chloride) is used in ceramic glazes, fire extinguishing, metallurgy, and highway de-icing and table salt.

In addition to analyzing the samples for the fibers and minerals found in common building materials, when a sufficient quantity of settled surface dust was present, it was mixed with water and the pH of the resulting mixture was measured.

Air Samples

Air samples were collected using vacuum pumps to draw air through a filter positioned at an adult's breathing level. In addition to a filter for fiber analysis, multiple particulate samplers were

http://www.atsdr.cdc.gOv/asbestos/lowemianhattan/ResSamp_Sep2002_Text.html 07/18/2003 NYC-WTC_000178393