ATSDR/DHAC_ASTM

NYC 9/11 Public Portal Document

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 (e.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 ciystalline 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 and tridymite 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 placed at each sampling location to collect different particle sizes including respirable (PM4 and PM2.5), thoracic (PM 10), and total inhalable (PM 100). This resulted in the collection of overlapping, or nested, particulate size fractions.

The particle size determines how deeply a particle can travel into the respiratory tract. Respirable particles with diameters of 4 microns or less (PM4) are very small particles that can be breathed in and can travel deeply into the air sacs of the lung. At some locations another sampler was used that collected a smaller set of respirable particles, those with diameters of 2V2 microns (PM2.5) or less. Another sampler collected particles with diameters of 10 microns (PM 10) or less. This sampler would collect not only respirable particles, but also those slightly larger particles that tend to land in the upper regions of the respiratory tract, including the throat. A fourth sampler collected a larger set of particles, those 100 microns (PM 100) or less in diameter. The larger particles in this fraction can land in the nose and throat. Where a particle lands determines what types of health effects might be experienced. Particles too large to travel into the narrower passages of the lower respiratory tract might deposit in the upper airways (e.g., the nose and throat) and cause irritation. Similarly, larger particles might cause eye irritation. If the settled surface dust contains sufficient amounts of particles of a very small size, then effects consistent with particles reaching the lower respiratory tract might occur (coughing, shortness of breath).

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