NYC Law Department letter regarding EPA draft report excerpts, July

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page34of56 SVF are all found at higher percentages in the samples from lower Manhattan when compared to the sampled areas above 59th Street. These findings are based on comparing the percent of each mineral and fiber In the settled surface dust. However, to determine the total mineral and fiber content In a room, the amount of dust present would also need to be known. Because surface loading Is not known, we cannot demonstrate that the total amount of mineral and fiber Is Increased In any given area. However, these data indicate the components and quality of the dust In lower Manhattan is different from that of the comparison areas above 59th Street.

The Increased crystalline minerals and fibers In the settled surface dust indicate a potential for contact with these materials. The magnitude of this contact will vary with dust loading (which is unknown) and activity In the area. Residents may come into contact with the dust directly (i.e., skin, eyes). Additionally, the dust may also become re-suspended In the air through activities such as cleaning. In this way the settled surface dust may be a reservoir for material In the air. Therefore settled surface dust results are important both to evaluate direct contact, as well as to evaluate the potential for airborne/Inhalation exposures.

6. Significance of Minerals and Fibers In Air

The settled surface dust samples suggest the potential for airborne particles and fibers. The air samples taken indicate that some of these materials are present In the air at measurable levels. Because the air samples were taken over several hours, they provide an understanding of average air levels over the course of the day. Some of these air samples were taken during normal dally activity outdoors in common areas and In residences. They represent the impact of vehicular traffic, walking, and normal activity In the area. As such they are a good measure of average exposure at that time and place. No samples were taken to assess high levels of activity, such as cleaning, which might generate short-term periods of higher levels of materials in the air. However, about 40% of the residences were aggressively sampled, which gives some Indication of the Impact of Increased activity on airborne levels.

Although semiquantitative, the minerals detected In air provide important information. Quartz and mica, which have potential health effects on the lung, were found in the respirable fraction of the dust (PM4). This Indicates that some portion of the quartz and mica found In the settled surface dust is of respirable size. Minerals found In the larger size air fractions, thoracic (PM10} and inhalable (PM100), Indicate that larger particles may also be present that could Irritate the upper areas of the respiratory tract. It should be noted that these larger fractions also Include thoracic and resplrable material.

The fiber analysis by PCM provides an upper bound of airborne fibers. Although fiber type Is not Identified In this analysis, there can be no more asbestos fibers than total fibers detected. Re- analysis of some of these samples shows that very few fibers of public health Interest (SVF or asbestos) were present. However, care must be taken when Interpreting these results because there

http://www.atsdr.cdc.gov/asbestos/lowennanhattan/ResSamp_Sep2002_Text.html 07/18/2003

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