Final Technical Report of the Public Health Investigation

to Assess Potential Exposures to Airborne and Settled Surface Dust

in Residential Areas of Lower Manhattan

September 2002

New York City Department of Health and Mental Hygiene

and

Agency for Toxic Substances and Disease Registry

U.S. Department of Health and Human Services

As a part of the

World Trade Center Environmental Assessment Working Group
September 11, 2001

In remembrance of those who were lost on September 11, 2001, and to the families and friends who will love them 

forever and keep their memories alive.

In grateful recognition of the countless responders and the many who supported their efforts.

New York City Department of Health and Mental Hygiene

U.S. Agency for Toxic Substances and Disease Registry
i

CONTENTS

Page

LIST OF TABLES iv

LIST OF FIGURES v

LIST OF SAMPLING EVENT PHOTOGRAPHS vii

EXECUTIVE SUMMARY 1

ABSTRACT 9

INTRODUCTION 10

BACKGROUND 10

A. World Trade Center Towers 10

B. Potential Contaminants 11

C. Monitoring in Lower Manhattan After the Collapse of the 

World Trade Center 11

D. Community Exposures 12

E. Human Health Effects of Concern 12

OBJECTIVES 12

METHODS 13

A. Sampling Approach 13

B. Samples Taken 13

C. Field and Laboratory Changes From the Original Sampling Protocol 14

1. Field Changes 14

2. Sample Analysis Changes 15

D. Data Management and Quality Assurance/Quality Control Procedures 15

E. Data Analysis 17

F. Limitations and Uncertainties 17

RESULTS 18

A. Survey 18

B. Settled Surface Dust 19

1. Fiber Analysis of Settled Surface Dust 19

2. Mineral Analysis of Settled Surface Dust 20

3. Alkalinity of Settled Surface Dust 22

C. Air 22
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Page

1. Fibers in Air 23

a. Indoor Air 23

b. Outdoor Air 24

2. Minerals in Air 24

DISCUSSION 26

A. Discussion of Results 26

1. Association of Asbestos and Synthetic Vitreous Fibers 27

2. Association of Asbestos and Synthetic Vitreous Fiber 

Levels Outside of and Within a Building 27

3. Occurrence of Crystalline Minerals 28

4. Buildings Impacted by Asbestos, Synthetic Vitreous Fibers,

and Crystalline Minerals 28

5. Significance of Minerals and Fibers in the Settled Surface Dust 29

6. Significance of Minerals and Fibers in Air 29

B. Public Health Evaluation 30

1. Sensitive Populations 31

2. Soluble Minerals: Gypsum, Portlandite, and Calcite 32

3. Mica 33

4. Halite 34

5. Crystalline Silica (Quartz and Cristobalite) 34

a. Silicosis 34

b. Lung Cancer 35

6. Synthetic Vitreous Fibers 36

a. Irritant Effects 36

b. Pulmonary Effects 37

7. Asbestos 38

a. Asbestosis 38

b. Lung Cancer and Mesothelioma 39

8. Multiple Material Exposures 40

a. Irritant Effects 40

b. Noncancer Pulmonary Effects 40

CONCLUSIONS 41

RECOMMENDATIONS 43

PUBLIC HEALTH ACTION PLAN 44

A. Public Health Actions Taken 44

B. Public Health Actions Planned 45
iii

Page

REFERENCES 46

AUTHORS AND ACKNOWLEDGMENTS 51

TABLES 54

FIGURES 64

SAMPLING EVENT PHOTOGRAPHS 82

APPENDICES 87

A. Particulate Matter Quality Assurance/Quality Control Discussion 88

B. Survey Results 92

C. Detailed Analytical Results 99
iv

LIST OF TABLES

Page

Table 1. General Information on the World Trade Center Towers 55

Table 2. 2000 Census Block Level Population 55

Table 3. Number of Buildings and Areas Within Buildings Sampled for 

Settled Surface Dust: Analyzed for Asbestos by PLM and TEM, 

SVF by PLM, and Minerals by XRD 56

Table 4. Number of Buildings and Areas Within Buildings Sampled for 

Fibers in Air: Analyzed for Total Fibers by PCM, Asbestos 

by TEM, and SVF by SEM 56

Table 5. Number of Locations Sampled for Minerals in Airborne Dust: 

Analyzed by XRD for Minerals 56

Table 6. Summary of Locations With Asbestos or Synthetic Vitreous 

Fibers (SVF) in Settled Surface Dust 57

Table 7. Summary of Mineral Components of Settled Surface 

Dust by Sampling Location 58

Table 8. Summary of Results for Locations With Airborne Fiber Levels Higher 

Than Levels in Comparison Areas Above 59th Street 59

Table 9. Summary of Airborne Fibers at Locations Where Asbestos Was 

Detected in Settled Surface Dust 60

Table 10. Summary of Airborne Fibers at Location Where Only Synthetic 

Vitreous Fibers (SVF) Were Detected in Settled Surface Dust 61

Table 11. Summary of Minerals in Indoor and Outdoor Air From Lower 

Manhattan and Comparison Buildings Above 59th Street 62

Table 12. Highest Amount of Materials Measured in the Indoor Settled 

Dust of Each Building 63
v

LIST OF FIGURES

Page

Figure 1. Buildings Damaged in Lower Manhattan, September 11, 2001 65

Figure 2. Lower Manhattan Residential Buildings With Pedestrian and 

Vehicular Traffic Restrictions 66

Figure 3. Residential Buildings in Lower Manhattan 67

Figure 4. Lower Manhattan Demographic Information—2000 Census 68

Figure 5. Lower Manhattan Ambient Air Sampling Locations—During 

the First Few Weeks After September 11, 2001 69

Figure 6. Residential Buildings Sampled, New York,

November 4–December 11, 2001 70

Figure 7. Residential Environmental Sampling—Lower Manhattan, 

Airborne Total Fibers (PCM), November 4–December 11, 2001 71

Figure 8. Residential Environmental Sampling—Lower Manhattan, 

Asbestos in Dust (PLM), November 4–December 11, 2001 72

Figure 9. Residential Environmental Sampling—Lower Manhattan,

Asbestos in Dust (TEM), November 4–December 11, 2001 73

Figure 10. Residential Environmental Sampling—Lower Manhattan,

Asbestos in Dust (PLM/TEM), November 4–December 11, 2001 74

Figure 11. Residential Environmental Sampling—Lower Manhattan,

Synthetic Vitreous Fibers in Dust (SVF),

November 4–December 11, 2001 75

Figure 12. Residential Environmental Sampling—Lower Manhattan,

Maximum Mineral Concentrations in Indoor Dust,

November 4–December 11, 2001 76

Figure 13. Residential Environmental Sampling—Lower Manhattan,

Calcite in Dust, November 4–December 11, 2001 77
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Page

Figure 14. Residential Environmental Sampling—Lower Manhattan,

Gypsum in Dust, November 4–December 11, 2001 78

Figure 15. Residential Environmental Sampling—Lower Manhattan,

Portlandite in Dust, November 4–December 11, 2001 79

Figure 16. Residential Environmental Sampling—Lower Manhattan,

Crystalline Quartz in Dust, November 4–December 11, 2001 80

Figure 17. Residential Environmental Sampling—Lower Manhattan, 

Materials in Indoor Dust, November 4–December 11, 2001 81
vii

LIST OF SAMPLING EVENT PHOTOGRAPHS

Page

Photo 1. Residential Vacuum Sample 83

Photo 2. Residential Air Sampling 83

Photo 3. Residential Air Sampling 84

Photo 4. Residential Air Sampling 84

Photo 5. Residential Air Sampling 85

Photo 6. Residential Air Sampling 85

Photo 7. Outside Bulk Sampling 86

Photo 8. Sampling Head 86
1

EXECUTIVE SUMMARY

From November 4 through December 11, 2001, environmental samples were collected in 

and around 30 residential buildings in lower Manhattan. In addition, four buildings above 

59th Street were sampled and used as a comparison area for this investigation. The New 

York City Department of Health and Mental Hygiene (NYC DOHMH) and the U.S. Agency 

for Toxic Substances and Disease Registry (ATSDR) conducted this limited investigation 

with support and collaboration from the U.S. Public Health Service Commissioned Corps 

Readiness Force and the World Trade Center Environmental Assessment Working Group. 

The purpose of the sampling was to assess the composition of both outdoor and indoor 

settled surface and airborne dust within residential areas around the World Trade Center. 

This information was used to help determine whether additional public health actions are 

needed to address any remaining World Trade Center-related dust inside residential areas. 

The information collected could also be used to compare the findings from the locations 

that were known or were likely to have received dust directly from the collapse of the 

World Trade Center towers, to findings from areas that were unlikely to have received dust 

directly from the disaster (comparison areas).

Attention was given to those materials reasonably expected to be in the original dust cloud 

and in dust generated by ongoing activities at the World Trade Center. The focus was on 

building materials that have been shown to have irritant properties (e.g., synthetic vitreous 

fibers [SVF] and gypsum) and be associated with long-term health concerns (i.e., 

crystalline silica and asbestos). The samples collected during this investigation were 

analyzed for the following materials: asbestos, SVF, mineral components of concrete 

(crystalline silica, calcite, and portlandite), and mineral components of building wallboard 

(gypsum, mica, and halite). Efforts were made to get as much 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 
2

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 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 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 (PM10), and total inhalable (PM100). 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 21⁄2 microns (PM2.5) or less. Another sampler collected particles with 

diameters of 10 microns (PM10) 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 (PM100) 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).
3

Each of the particulate air sample fractions was analyzed for crystalline minerals (quartz, 

cristobalite, tridymite, calcite, portlandite, gypsum, mica, and halite). X-ray diffraction 

analysis (XRD) identifies a mineral by the unique diffraction pattern given off when the xray strikes its surface. The diffraction pattern serves as a “fingerprint” to identify the 

mineral present.

Other air samples were screened for fibers using phase contrast microscopy (PCM) to 

count the total number of all fibers present. If the concentration of total fibers was higher 

than the maximum concentration of fibers found in the comparison homes (0.003 fibers per 

cubic centimeter of air) the sample was re-analyzed for asbestos by transmission electron 

microscopy (TEM). Additionally, scanning electron microscopy (SEM) was used to look 

for SVF if the PCM fiber counts was higher than 0.003 fibers per cubic centimeter (f/cc) 

and if the settled surface dust sample from that area contained SVF.

Settled Surface Dust Samples

The composition of settled surface dust reflects particles and fibers that have been tracked 

into an area or that were present in the air and have with time, deposited on surfaces. 

Settled surface dust was collected indoors using a specialized vacuum cleaner. Outside 

settled surface dust was collected by scooping any visible dust-type material into a 

container. As with the air samples, the settled surface dust samples were analyzed to 

assess the presence of fibers and minerals. The analysis performed does not allow the 

determination of what size particles are present in the dust. The composition of the settled 

surface dust was evaluated to determine if, on the basis of its composition, it could be an 

irritant if it became airborne or came in contact with skin or eyes during cleaning 

activities.

The dust samples were analyzed for the presence of asbestos and SVF using polarized light 

microscopy (PLM). PLM can distinguish between fiber types by their unique appearance 

and color when viewed under different wavelengths of light. In addition, TEM analysis 

was conducted on all dust samples that showed asbestos content by PLM as less than 1%. 

TEM analysis is very specific, can detect smaller fibers of asbestos, and is subject to less 

interference than PLM.

The dust samples were also analyzed for mineral content using XRD as described 

previously for the air samples. For the dust samples, the mineral and the fiber results are 

expressed as a percent, indicating the weight percent each component represents in the 

portion of the dust sample analyzed. The different analytical techniques, XRD and 

microscopy (PLM, TEM, SEM), help to characterize what was in the settled surface dust; 

however the results from the two methods each performed on a portion of the dust 

collected, cannot simply be added together to “sum up” what was in the dust. XRD results 

are based upon the weight of the dust sample analyzed. While, PLM, TEM, and SEM 

results are based on the surface area viewed under the microscope.
4

Limitations

While the goal of the sampling was to evaluate the air and dust samples for a range of 

contaminants, there is no one sample collection method or analysis that can provide all of 

the determinations that were desired. The analysis strategy was to identify what 

components were present in order to provide the public with information quickly if any of 

the analyses revealed a significant concern. In order to strive for both of those goals, some 

modifications to conventional protocols were made which limited some analyses from 

determining the precise level of the materials in the sample (e.g., XRD conducted on air 

and dust samples). Whenever an analysis is expanded beyond its specific intent, there is the 

potential loss of sensitivity and an increase in the variability in the data. Those particular 

analytical results are reported as estimated values and marked with a “J.”

Results for the airborne particulate matter were rejected due to issues found during the 

quality assurance analysis. However, the XRD analysis for airborne minerals that used the 

same filter samples as the particulate matter analysis are considered valid because the 

analysis method does not depend on the filter sample weighing process used to determine 

the particulate matter concentration. The XRD mineral air concentrations are based on 

individual mineral weight standard curves—not the weight of the dust sample collected on 

the filters. These standard curves are not impacted by pre- and post-sampling filter weight 

variability.

Air Sampling Results 

Total fiber counts of air samples taken in lower Manhattan were similar to the comparison 

areas above 59th Street sampled during this investigation. The six lower Manhattan areas 

that had elevated total fiber counts were re-examined by TEM and SEM to determine the 

types of fibers. The TEM and SEM results indicated that neither asbestos nor synthetic 

vitreous fibers (e.g., fiberglass) contributed to the elevated total fiber counts.

Air sampling results for minerals detected quartz (a form of crystalline silica) and other 

building-related materials in lower Manhattan. The other forms of crystalline silica were 

not detected in any air samples except for a one-time detection of cristobalite. The 

estimated concentrations of these minerals in air were low. In some locations, mineral 

components of concrete (quartz, calcite, and portlandite) and mineral components of 

building wallboard (gypsum, mica, and halite) were detected in air samples at higher 

estimated levels in lower Manhattan residential areas than in samples taken at comparison 

residential areas above 59th Street. The levels of minerals seen in airborne dust do not 

pose potential health hazards even for a continuous year of exposure at the highest levels 

detected.

Settled Surface Dust Results

Results of the settled surface dust analysis indicate the composition of settled surface dust 

in lower Manhattan is different than the dust analyzed from the comparison areas above 

59th Street. Although the materials found are consistent with materials expected from the 
5

World Trade Center collapse, these results cannot determine the actual source of the 

materials present because these materials are common building components and can come 

from other sources in a busy urban area.

In lower Manhattan, asbestos was found in indoor dust in 15 of 83 (18%) samples from 

residential units and common areas at levels ranging from less than 1% (<1%) to 1.5%. 

Asbestos was detected in 6 of 14 (43%) outdoor samples at levels ranging from <1% to 

3.4%. Indoor settled surface dust contained SVF in 40 of 83 (48%) locations ranging from 

2% to 35% of the dust content. SVF was detected in 11 of 14 (79%) outdoor locations at 

levels ranging from 1% to 72%. No asbestos or SVF was detected in dust in the 

comparison areas above 59th Street.

The XRD analysis for crystalline minerals in settled surface dust is semiquantitative 

(estimated values, indicated by “J”). However, quartz, calcite, portlandite and gypsum 

appear to make up a higher percentage of dust in some buildings in lower Manhattan when 

compared to settled surface dust samples from buildings above 59th Street. Quartz was 

detected up to an estimated 31%J versus up to 2%J found in the comparison areas above 

59th Street. Neither cristobalite nor tridymite was detected in any of the settled surface 

dust samples. Similarly gypsum was found at a maximum estimated concentration of 30%J 

in settled surface dust, higher than the 4%J estimated in the comparison areas above 59th 

Street. Calcite and portlandite had maximum concentrations of 21%J and 8%J respectively. 

At lower Manhattan locations sampled, quartz was detected in 81% of common areas and 

53% of residences. Gypsum was seen in 88% of common areas and 79% of residences. 

Minerals were found in all lower Manhattan outdoor settled surface dust samples at 

estimated values ranging as high as 27%J quartz, 19%J calcite, 6%J portlandite, and 27%J 

gypsum. No visible settled outdoor dust was available in the comparison areas above 59th 

Street.

Several of the minerals detected in the settled surface dust samples, such as portlandite and 

calcite, can make the dust more alkaline, or raise the pH. Only two dust samples provided 

enough material for the determination of pH. The samples, collected from two outdoor 

locations in lower Manhattan, had pH levels of 8.6 and 9.8. On the pH scale, values less 

than 7 are considered acidic, a value of 7 is neutral, and values above 7 are alkaline or 

basic. Based on the results of the pH analyses, these dust samples are slightly alkaline. 

This is consistent with the detection of portlandite and calcite (alkaline minerals present in 

concrete) in the mineral analysis of the dust sample from the same location.

Conclusions 

Based upon the analytical results of samples taken between November 4 through December 

11, 2001, and information collected during the sampling effort, the New York City 

Department of Health and Mental Hygiene and the U.S. Agency for Toxic Substances and 

Disease Registry make the following conclusions (not in order of importance).
6

• Total fiber counts of air samples taken in lower Manhattan were similar to the 

comparison areas above 59th Street sampled during this investigation. The six 

lower Manhattan areas that had elevated total fiber counts were re-examined by 

transmission electron microscopy (TEM) and scanning electron microscopy 

(SEM). The TEM and SEM results indicated that neither asbestos nor SVF 

contributed to the elevated fiber counts.

• Low levels of asbestos were found in some settled surface dust, primarily below 

Chambers Street. Many of the lower Manhattan locations sampled had been 

previously cleaned prior to this investigation. No asbestos was detected in the 

comparison indoor dust samples taken north of 59thStreet. The City of New York 

has conducted follow-up activities at the locations where asbestos was detected in 

settled surface dust. Only two follow-up locations, outdoor areas, required 

professional asbestos abatement. Following-up activity at the other locations did 

not find any asbestos containing materials.

• When compared with the results obtained from the comparison sampling 

locations, the lower Manhattan residential areas sampled by this investigation 

tended to have a greater percentage of SVF (primarily fiberglass), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum, mica, and halite) in settled surface dust. However, 

the frequency of detections and prevalence patterns of these minerals are similar in 

both residential areas.

• Exposure to significant amounts of synthetic vitreous fibers (SVF), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum) may cause skin rashes, eye irritation, and upper 

respiratory irritation, all of which have been voiced as concerns by citizens and 

first responders. If the reported irritant effects are associated with World Trade 

Center related materials, these effects will subside once exposure to SVF, mineral 

components of concrete, and mineral components of building wallboard end. Some 

people with pre-existing heart or lung disease (e.g., asthma) or a previous history 

of very high levels of exposures (occupational) to SVF, mineral components of 

concrete, and mineral components may be more sensitive to the irritant effects of 

SVF, mineral components of concrete, and mineral components of building 

wallboard.

• Sometimes mineral components of concrete (calcite and portlandite) and mineral 

components of building wallboard (gypsum, mica, and halite) were detected in air 

samples at higher estimated levels in lower Manhattan residential areas than in 

samples taken at comparison residential areas. These detected mineral levels are 

orders of magnitude below occupational standards. Although the occupational 

standards do not account for sensitive individuals or extended periods of exposure, 

they provide a comparison to an established health guidance value. The levels of 

minerals seen in airborne dust do not pose potential health hazards even for a 

continuous year of exposure at the highest levels detected.
7

• Some settled surface dust could become airborne if disturbed. Therefore, people 

could potentially inhale the asbestos, SVF, mineral components of concrete (quartz, 

calcite, and portlandite), and mineral components of building wallboard (gypsum, 

mica, and halite) found in settled surface dust of some lower Manhattan residences. 

Because we did not determine the weight of dust present in the areas sampled, it is 

not possible to determine whether any particular residence had an elevated dust 

loading. Appropriate continued frequent cleaning should minimize exposures.

• Several worst-case assumptions were made in order to assess the potential longterm public health risks of airborne asbestos and quartz. Some of the assumptions 

were that no cleaning of indoor spaces has occurred or will occur, all fibers found 

in air were asbestos fibers, and the highest levels detected last fall in air represent 

long-term air levels. Using these worst-case assumptions, prolonged exposure 

(decades) to airborne asbestos and quartz may increase the long-term, theoretical 

risk of people developing lung cancer and other adverse lung health effects (more 

than 1 additional case in 10,000 people exposed). For individuals who conduct 

frequent cleaning of their residences, as recommended in this report, or participate 

in the U.S. Environmental Protection Agency cleaning/sampling program, it is 

unlikely that their exposure would resemble these worst-case conditions. 

• A review of the building sampling results from this investigation indicates that 

there is not a consistent spatial distribution pattern of asbestos, SVF, mineral 

components of concrete, and mineral components of wallboard in air and settled 

surface dust. This indicates that the materials are heterogeneously distributed. 

There are many factors that may contribute to the heterogeneous distribution, 

including whether the area was cleaned (indoors and outdoors), cleaning method, 

date since last cleaning, and how much dust was initially in the area. It is not clear 

which factors contributed to this pattern.

• 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 

may or may not reflect 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).
8

Recommendations

Based upon the conclusions of this investigation, the New York City Department of Health 

and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease Registry make 

the following recommendations.

• Because more asbestos, synthetic vitreous fibers (e.g., fiberglass), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum, mica, and halite) were found in settled surface dust 

in lower Manhattan residential areas when compared to comparison residential 

areas, the New York City Department of Health and Mental Hygiene and the U.S. 

Agency for Toxic Substances and Disease Registry are recommending that people 

continue to conduct frequent cleaning with HEPA vacuums and damp cloths/mops 

to reduce the potential for exposure.

• To ensure that the recommended frequent cleaning is effective and to ensure that 

the health of the people of New York City is protected, the New York City 

Department of Health and Mental Hygiene and the U.S. Agency for Toxic 

Substances and Disease Registry are recommending additional monitoring of 

residential areas in lower Manhattan. In addition, an investigation should be 

conducted to better define background levels specific to the city of New York for 

asbestos, synthetic vitreous fibers, mineral components of concrete (quartz, calcite, 

and portlandite), and mineral components of building wallboard (gypsum, mica, 

and halite).

• Lower Manhattan residents concerned about possible World Trade Centerrelated dust in their residential areas can request cleaning and/or testing from the 

U.S. Environmental Protection Agency (EPA) by logging on to the agency's World 

Trade Center Web page at www.epa.gov/wtc or by calling the EPA hotline at 1-

877-796-5471.
9

ABSTRACT

The New York City Department of Health and Mental Hygiene and the U.S. Agency for 

Toxic Substances and Disease Registry in collaboration with the U.S. Public Health 

Service Commissioned Corps Readiness Force and the World Trade Center Environmental 

Assessment Working Group conducted a limited investigation of residential areas near and 

around the World Trade Center (WTC). The purpose of the investigation was to assess 

potential exposures to airborne and settled surface dust that entered residential areas 

following the collapse of the WTC buildings.

Sampling of the residential areas occurred from November 4 through December 11, 2001, 

and was conducted by U.S. Public Health Service Commissioned officers detailed to the 

New York City Department of Health and Mental Hygiene with assistance from the New 

York City Department of Health and Mental Hygiene. 

The results of this investigation do not necessarily reflect levels that would be found in 

other lower Manhattan buildings or residential areas; the measurements reflect levels that 

were present at the time of sampling in the specific residential areas sampled. The limited 

number of results obtained from the comparison areas above 59th Street may or may not 

reflect the New York City-specific background levels of asbestos, synthetic vitreous fibers 

(SVF), mineral components of concrete (quartz, calcite, and portlandite), and mineral 

components of building wallboard (gypsum, mica, and halite).

Low levels of asbestos were found in some indoor and outdoor settled surface dust, 

primarily below Chambers Street. Many of the lower Manhattan locations sampled had 

been cleaned prior to this investigation. No asbestos was detected in the comparison 

indoor dust samples taken north of 59th Street. Not enough visible settled dust was 

available to collect outdoor samples in the comparison area. When compared with the 

results obtained from the sampling locations above 59 Street, the lower Manhattan 

residential area settled surface dust sampling results tended to have higher percentages of 

SVF, mineral components of concrete (quartz, calcite, and portlandite), and mineral 

components of building wallboard (gypsum, mica, and halite) in settled surface dust. 

Because asbestos, SVF, mineral components of concrete (quartz, calcite, and portlandite), 

and mineral components of building wallboard (gypsum, mica, and halite) were found at 

higher levels in settled surface dust in lower Manhattan residential areas when compared 

to comparison residential areas above 59th Street, the New York City Department of 

Health and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease 

Registry are recommending that people continue to conduct frequent cleaning with HEPA 

vacuums and damp cloths/mops to reduce the potential for exposure and/or participate in 

the U.S. Environmental Protection Agency cleaning/sampling program.

Total fiber counts of air samples taken in lower Manhattan were similar to the comparison 

areas above 59th Street sampled during this investigation. The six lower Manhattan areas 

that had elevated total fiber counts were re-examined by transmission electron microscopy 

(TEM) and scanning electron microscopy (SEM). The TEM and SEM results indicated that 
10

neither asbestos nor SVF contributed to the elevated fiber counts. Sometimes mineral 

components of concrete (calcite and portlandite) and mineral components of building 

wallboard (gypsum, mica, and halite) were detected in air samples at higher estimated 

levels in lower Manhattan residential areas than in samples taken at comparison residential 

areas. These detected mineral levels are orders of magnitude below occupational 

standards. Although the occupational standards do not account for sensitive individuals or 

extended periods of exposure, they provide a comparison to an established health guidance 

value. The levels of minerals seen in airborne dust do not pose potential health hazards 

even for a continuous year of exposure at the highest levels detected.

INTRODUCTION

At 8:45 AM eastern standard time on September 11, 2001, a commercial jetliner struck the 

north tower of the World Trade Center (One World Trade Center). At 9:03 AM, the south 

tower (Two World Trade Center) was also struck by a commercial jetliner. The south 

tower began to collapse at 10:05 AM. At 10:30 AM, the north tower began to collapse. 

(1,2,3,4) 

The collapse of these structures released massive amounts of dust and debris that covered 

lower Manhattan. Residents were evacuated from many areas south of Canal Street. On 

September 19, pedestrian and vehicular traffic restrictions for below Canal Street were 

modified (5). As residents moved back into the areas, they requested information on the 

safety of the dust and air in the area and the types of cleaning methods that should be used. 

The New York City Department of Health and Mental Hygiene provided guidance on 

cleaning for area residents and requested federal assistance in assessing potential 

exposures to airborne and settled surface dust that entered residential areas following the 

collapse of the World Trade Center (WTC) buildings.

BACKGROUND

A. World Trade Center Towers

The World Trade Center was a complex of 7 buildings on 16 acres surrounding a 5-acre 

plaza in lower Manhattan. The complex was bounded by Vesey Street on the north, Church 

Street on the east, Liberty Street on the south, and West Street on the west. The twin towers 

were the center of the complex. Each tower had 110 floors; the north tower was 1,368 feet 

tall and the south tower was l,362 feet tall. Each tower had approximately 43,200 square 

feet on each floor. There were seven underground levels that contained services, shopping 

areas, and a subway station. There were two plaza buildings (WTC 4 and WTC 5) on 

Church Street that had nine stories. WTC 7 was a 47-story office building. Design and 

structure details of the towers are shown in Table 1 (1,2,3,4,6). Basic location and U.S. 

Census population information about lower Manhattan is provided in Table 2 and Figures 

1 through 4.
11

B. Potential Contaminants 

The dust cloud released at the collapse of the buildings was comprised of materials that 

were used in the construction of the buildings (such as concrete and insulation materials). 

In addition to the dust cloud from the building collapse, contaminants were released in 

fires fed by jet fuel and the combustible materials in the buildings.

The dust contained the constituents of concrete, wallboard, and insulation. Concrete is a 

mixture of cement, aggregate (sand and gravel), and water. Cement contains limestone, 

clay, gypsum, and metals. Sometimes other minerals (such as fly ash or crystalline silica) 

are added to concrete to change its properties. Concrete tends to have a high pH, and if 

dust from the concrete was mixed with moisture, the resulting solution would tend to have a 

high pH. Asbestos was used as insulation in a portion of the towers. Fiberglass, a synthetic 

vitreous fiber, was also used as insulation in the buildings and is likely to have been used 

in building furnishings. Surface dust and debris containing asbestos have been found in 

lower Manhattan. Asbestos was detected in the personal air samplers of rescue and 

recovery workers. In addition, low levels of asbestos, fibrous glass, and the constituents of 

concrete and wallboard have been detected in air samples collected at the WTC site 

perimeter. These materials are common building components, and there are other sources 

of these materials in any large urban areas.

C. Monitoring in Lower Manhattan After the Collapse of the World Trade Center

The U.S. Environmental Protection Agency (EPA) and other federal, state, local agencies, 

and private firms have been conducting environmental monitoring in a variety of media 

since September 11 (some of the ambient air sampling locations are depicted on Figure 5). 

In November 2001, EPA tasked the IT Corporation Quality Assurance Technical Support 

Program contractor to evaluate the environmental monitoring data that had been collected. 

Through April 24, 2002, there were approximately 263,000 sample results analyzed (7). 

There were 605 analytics that were included in the database such as asbestos, fibers, 

particulates, metals, volatile organic compounds (VOCs), polycyclic aromatic 

hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The greatest number of 

analytical samples was collected for analysis of total fiber concentration, asbestos fiber 

concentration, or the percentage of asbestos. The overall largest number of samples in the 

monitoring was for particulate matter. The monitoring stations for particulate matter (rooftop locations) are a part of the New York State Department of Environmental Conservation 

air quality-monitoring program. Additional stations were added after the WTC towers 

collapsed.

The analytical results of air samples showed decreasing concentrations that appeared to 

have reached pre-existing background levels by the end of April 2002 (7). Bulk dust 

samples were tested for asbestos, dioxins/furans, PCBs, PAHs, and metals. The levels for 

some of the analytics (e.g., asbestos) were relatively high; however, only a few samples 

obtained after mid-October showed elevated levels (7).
12

In general, air monitoring near the WTC has not detected any pollutants from the fire and 

building collapses at levels that are of public health concern. Within the restricted zone 

(within one block of the WTC), low levels of asbestos have been found in the airborne dust 

from the building collapse (7). Bulk dust and air samples (mostly on or near the work site), 

as well as surface runoff water, river sediment, and river water have been analyzed for 

other contaminants, including metals, VOCs, PAHs, dioxins and PCBs. These contaminants 

were found at low levels that did not indicate a need to conduct further sampling for them 

at the time of the residential sampling (8).

D. Community Exposures

The most likely routes of community exposures to contaminants would be through breathing 

in airborne dust and through direct contact with surface dust and debris. The sampling plan 

was developed to determine the potential for exposure to building material-related 

contaminants in air and dust.

E. Human Health Effects of Concern

The primary health effects of immediate concern are respiratory effects and irritant effects 

from inhalation of or direct contact with building-related materials. Many of the materials 

expected to be in airborne dust can cause eye, nose, and throat irritation. In addition, those 

materials that can be inhaled or respired from airborne dust can cause respiratory irritation 

and exacerbation of pre-existing problems such as asthma, emphysema, and 

cardiopulmonary disease. Materials in the surface dust can cause skin irritation on contact. 

There have been reports of burning throat and eyes from residents returning to the area.

OBJECTIVES

The overall objective of this sampling was to provide results upon which public health 

agencies could further determine the potential for environmental exposures to WTC 

collapse-related materials and possible health implications of the exposures. Sampling 

was intended to better characterize ambient and indoor airborne and potentially airborne 

particles (surface dust) in residential areas of lower Manhattan from the collapse of WTC.

Specifically, the objective was to characterize the makeup and size distribution of airborne 

breathing zone dust in residential areas—both indoors and outside—near the WTC. This 

information was used to further determine whether materials were present in air at levels 

of public health concern and whether settled surface dust contained materials that could 

potentially be re-entrained and result in continued exposures.

Note: The sampling approach was focused on contaminants that emanated from the 

collapse of the WTC towers and that might cause health problems. However, this 

investigation could not conclude if contaminants or materials found actually came 

from the disaster. The contaminants that were selected for testing could be present in 

some areas from other sources. Some typical examples of this include cooking on a 

stove top, which can increase indoor airborne particulate matter; vehicle exhaust, 
13

which can increase outdoor airborne particulate matter; and recent home renovation 

activities, which can result in an increase in levels of gypsum, fiberglass, and other 

materials in air and surface dust.

METHODS

Details on the methods used in the residential sampling investigations are included in the 

residential sampling plan that is on the New York City Department of Health and Mental 

Hygiene’s Internet page (http://www.nyc.gov/html/doh/pdf/alerts/indoor1.pdf). Printed 

copies of the plan can be requested from the New York City Department of Health and 

Mental Hygiene.

A. Sampling Approach

A series of three concentric circles was drawn around the WTC location. The circles were 

then divided by direction or zone from the WTC (north, south, and west). Attempts were 

made to obtain access to the same number of residential buildings per zone for sampling. 

Four residential buildings above 59th Street were selected for testing to determine what 

levels of fibers and minerals might be routinely found in the city.

Once a building was selected, air and settled surface dust sampling occurred in up to four 

different locations: an area outdoors near a main entryway to the building; an area inside of 

the main entry (or other common area); and two residential units. Informed consent for 

sampling was obtained and questions were asked about details that could aid in 

interpreting the sampling results (such as whether the windows were open on the morning 

of September 11, 2001).

Both air and settled surface dust samples were collected in high traffic or routinely used 

areas of the space. For example, settled surface dust was collected from areas where 

individuals frequently walked, not from behind furniture or underneath kitchen appliances. 

Air sample inlets were at approximately 4 feet in height above the ground/floor surface to 

provide results more reflective of what might be inhaled.

Attempts were made during air sampling to obtain data that would reflect what might be in 

the air during periods of high activity. If the selected area was not occupied at the time of 

sampling, and if there was no central heating or air conditioning system that could result in 

contaminant migration into another occupied area, aggressive air sampling was conducted. 

If the area was occupied, the heating or air conditioning system fan was turned on during 

the period of sampling. This would not represent a period of high activity, but would 

present data that might be found during typical or normal activity.

B. Samples Taken

Sample collection was conducted from November 4, 2001, to December 11, 2001, for the 

lower Manhattan area and from December 6–10, 2001, for the comparison buildings above 

59th Street. Because of the limited and time critical essence of this investigation, thirty 
14

buildings in lower Manhattan were sampled, and four comparison buildings were sampled 

from the area north of 59th Street. In the 30 lower Manhattan buildings, the following 

locations were sampled: 59 residential units, 29 common areas, and 29 outdoor areas.

There were 127 air samples taken from 117 different areas of the lower Manhattan 

buildings. Ten of the areas had co-located sampling equipment. In the 59 different 

residential units, there were 64 air samples taken. Thirty air samples were taken from 29 

different common areas.

Samples taken from the four comparison buildings above 59th Street included three outside 

air samples, three of common areas with both indoor settled surface dust and air, and five 

residential units with both indoor settled surface dust and air. No outside settled surface 

dust samples were collected because there was no visible dust to collect.

Tables 3, 4, and 5 show the number of buildings and areas within the buildings that were 

sampled for asbestos, SVF, and minerals in lower Manhattan and the comparison units 

above 59th Street. The tables also show whether the samples were settled surface dust and 

air samples.

C. Field and Laboratory Changes From the Original Sampling Protocol

Once the sampling teams went to the various sampling locations, it was determined that 

some changes needed to be made to the sampling protocol. The sections below indicate the 

changes that were made to the original sampling protocol.

1. Field Changes

The sampling protocol indicated that a total of 60 residential units would be tested in 

lower Manhattan. A total of 59 residential units were sampled. 

Indoor settled surface dust was collected using EPA’s Environmental Response Team 

Standard Operating Procedure (ERT SOP) for household dust, as stated in the sampling 

protocol. However, due to cost and equipment availability constraints, Omega Ultivac 

vacuums with high efficiency particulate air (HEPA) filters were used instead of NilfiskTM

vacuums. To avoid the need to decontaminate the vacuum hose between each sampling 

event, a sample collection filter (Alsock, by Midwest Filtration) was inserted into the airintake end of the vacuum hose. The Alsock has a 97% capture of particles with diameters 

of 1.1 microns and larger. The ERT SOP-specified vacuum bag filter has a 4- to 5-micron 

pore size.

Instead of one settled surface dust sample per unit, two co-located indoor settled surface 

samples were collected. This change was made as two different laboratory locations were 

involved in the analysis. The EMSL Analytical laboratory in New York City analyzed 

samples for fibers (using PCM, PLM, and TEM); the EMSL Analytical laboratory in 

Westmont, New Jersey, analyzed samples for the remaining materials and conducted the 

SEM analysis for fibers.
15

Delays in obtaining equipment resulted in only 10 buildings being sampled for the PM2.5 

air fraction.

There was no visible settled surface dust around the comparison homes selected above 

59th Street; therefore, no outdoor settled surface dust samples were collected from the 

comparison areas above 59th Street.

2. Sample Analysis Changes

Airborne and settled surface dust samples were analyzed for crystalline silica using EMSL 

Analytical’s Material Science Division Operating Procedure MSD 0700, January 2000. 

XRD analysis was conducted for the nonsilica crystalline minerals in air and settled 

surface dust samples by EMSL using Material Science Division Operating Procedure MSD 

9300, January 2002. The samples were not ashed prior to XRD analysis for the following 

reasons: ashing samples could have resulted in loss or breakdown of analytes of interest 

including gypsum; and there was not enough organic material present to result in loss of 

method sensitivity for crystalline minerals of interest.

SEM analysis was conducted on air samples for fibrous glass and other synthetic vitreous 

fibers by EMSL using Material Science Division Operating Procedure MSD 0300. This 

analysis was conducted on all samples collected from the comparison areas above 59th 

Street and on only those air samples from lower Manhattan with PCM fiber concentrations 

higher than the comparison PCM fiber concentrations.

Settled surface dust samples were analyzed for fibrous glass by EMSL using New York 

State Department of Health Environmental Laboratory Approval Program Method 198.1 

polarized-light microscopy methods for identifying and quantifying asbestos in bulk 

samples.

Settled surface dust samples were not weighed, so surface loading of materials could not 

be calculated. Although settled surface dust samples were sieved, sieving was not 

conducted as specified in the ERT SOP. Rather, sieving was conducted as specified in 

MSD 0700 and 9300.

D. Data Management and Quality Assurance/Quality Control Procedures

EPA provided the laboratory used for this investigation. The laboratory is part of EPA’s 

“certified” Contract Laboratory Program. It used all of the EPA quality assurance/quality 

control laboratory methodologies when analyzing the samples collected for this 

investigation. EPA conducts audits of all the EPA-certified laboratories to assure that 

appropriate quality assurance/quality control laboratory methodologies are being used.

Chain-of-custody procedures were established and maintained throughout sample 

collection, transportation, and analysis of samples. These procedures helped to assure that 

analytical results could be matched to the sampling locations.
16

Following the sampling effort, more than 5,400 analytical results were individually 

returned from the laboratory. All results were entered into a Microsoft EXCEL spreadsheet 

along with the other raw data describing where and how the sample was taken. Asbestosin-air laboratory results were submitted calculated in concentration and were used as 

received. The laboratory typically submitted particulates-in-air results as the initial and 

final filter weights (pre- and post-sampling weights). The total amount of material 

deposited on the filter and resulting concentrations for the sampling location were 

estimated from the laboratory results. Results for asbestos, fiberglass, and mineral 

components in settled surface dust were used as provided by the laboratory: percentage of 

material analyzed.

All of the results were reviewed as a part of normal data quality analysis. The general 

purpose of this quality assurance/quality control (QA/QC) review is not to pronounce the 

data “accurate,” but to determine whether the results are obviously affected by sampling or 

analytical errors. For this investigation, the reported analytical results were accepted, 

rejected, or used conditionally. Decisions on how to treat a data set were made primarily 

by comparing the measured results to information gathered from the blanks using graphs 

and statistical analyses.

Most of the results were used as received from the laboratory. The laboratory reported the 

asbestos in air results as a concentration of asbestos in the sampled location. The asbestos 

and fibrous glass in airborne and settled surface dust were used as received.

Results for the airborne particulate matter were rejected due to issues found during the 

quality assurance analysis. Variability of field blank sample weights was beyond the 

acceptable limits. A more thorough discussion of why the airborne particulate matter 

results were rejected is located in Appendix A of this report.

The XRD analysis was conducted on the air samples collected for particulate matter 

(PM100, PM10, PM4, and PM2.5). The PM results were rejected, but the XRD results 

were accepted as semiquantitative. The XRD results are considered valid because the 

analysis method does not depend on the filter-weighing process used to determine PM 

concentration. The XRD mineral concentrations are based on individual mineral weight 

standard curves—not the weight of the dust sample collected. These standard curves are 

not impacted by pre- and post-sampling filter weight variability.

Minerals were not detected on the blank air samples. This indicates that sample 

contamination or cross-contamination did not occur during air sampling, shipping, or 

sample analysis. The XRD information for the air samples provided semiquantitative 

values (estimated values, indicated by “J”). The PM100 and PM10 results may be potential 

overestimates, as the crystalline mineral size used for the standard curve is close to PM4 in 

size. This will result in the XRD overestimating the concentration of minerals present in 

the larger fractions. Similarly, the PM2.5 results may be potential underestimates of 

mineral concentrations.
17

The XRD settled surface dust results are also considered semiquantitative (“J”) due to 

particle sizes used for standard curve/calibration (as described for the air samples) and 

due to the lack of standard analytical error (SAE) information from the laboratory.

E. Data Analysis

The data were entered into an Excel spreadsheet, and descriptive statistics were 

developed for the sample results. Basic trend analysis on the analytical data was conducted 

using the SAS statistical program (version 8.01). The SAS System is an integrated system 

of software providing complete control over data access, management, analysis, and 

presentations. Examples of some of the SAS procedures (“Proc”) used were the “Proc 

Mean” and “Proc t-Test.”

F. Limitations and Uncertainties

The intent of the sampling was not to characterize the total extent of contamination in lower 

Manhattan or determine the extent of exposures for all people in lower Manhattan that may 

have resulted from the collapse of the WTC towers. Rather, it was a preliminary 

investigation to determine if building collapse-related materials could be present at levels 

of possible health concern in lower Manhattan. 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.

Some uncertainties tend to underestimate the risk of exposure while other uncertainties tend 

to overestimate the risk of exposure.

• The locations selected for sampling within each building may not be representative of 

the rest of the building; the building-specific results may either overestimate or 

underestimate the levels of WTC-related materials in other areas of the building.

• Sampling was conducted in November and December of 2001. Levels of particulate 

matter and airborne irritants were likely to have been higher in the days and weeks 

immediately after the WTC collapse. Levels of settled surface dust were likely higher as 

well. Outdoor dust contamination would have been reduced by wind, rain, and cleaning 

(HEPA trucks to vacuum the streets and sidewalks). Indoor settled surface dust may have 

been reduced if appropriate cleaning had been conducted prior to this sampling event. 

Therefore, these results serve as estimates, and are not necessarily reflective of conditions 

at earlier time points or of current conditions.

• Likewise, if continued cleaning has occurred since the November–December 2001 

sampling event, levels of contaminants should be lower today. Therefore, the results of this 

sampling effort would tend to overestimate the current levels of WTC-related materials in 

the buildings.
18

Uncertainty also exists in determining at what level and duration of exposure people might 

experience irritation or other symptoms from exposure to fibers and crystalline minerals.

• The likelihood of experiencing irritation from individual contaminants or contaminant 

mixtures is uncertain. A short exposure to a small amount of an irritant may be tolerated, 

but exposures that continue for a longer period of time or are to a larger amount of an 

irritant, may overwhelm the body’s ability to remove the irritant and increase the 

likelihood of irritation. Individual differences also play a significant role in whether or not 

irritation occurs. Using a risk estimate from an occupational situation may underestimate

risks for more sensitive or susceptible individuals in the general population. Some of the 

information needed to estimate the risk of irritant symptoms, is not available from this 

study. When assumptions are made in the absence information (e.g., the duration and 

intensity of the total exposure) additional uncertainty is introduced.

• Persons with pre-existing respiratory (e.g., asthma, emphysema) or cardiopulmonary 

problems are more likely than healthy individuals to experience adverse health symptoms 

at lower levels of airborne particles and contaminants. Airborne dust and crystalline 

mineral levels based on studies of healthy individuals are levels that underestimate the 

risk for a susceptible individual.

• Individuals who were in the lower Manhattan area when the WTC collapse occurred 

may have received a bolus inhalation dose of dust, fibers, crystalline minerals, and other 

materials. Health effects of a bolus dose are not known. Additional exposures would add 

to the potential for health effects. Therefore, the short and long-term health effects, if any, 

of such an exposure cannot be determined from the measurements made in this study.

RESULTS

This section of the report will provide an overview of what was determined by this 

investigation. The overall analytical findings will be presented according to what 

environmental media was sampled (air or settled surface dust, Figures 7-17).

A. Survey

The primary duty of the sampling team was to coordinate with the building management to 

identify sampling locations that would yield results representative of the area sampled. 

These duties included identifying unoccupied residences that could have aggressive air 

sampling conducted. In addition the sampling teams photographed equipment setup and 

operation, sampling locations, distribution of surface dust, and general conditions around 

the building.
19

The sampling team completed building surveys, in part, to gather the information needed to 

cite sample locations and to provide information to be used in interpreting the results. 

These surveys were completed on the basis of their observations and on discussions with 

building management when representatives were available. However, information was not 

always available to completely answer each survey question. This was especially true 

when evaluating specifics of the heating and air conditioning systems. The validity of the 

information is dependent on the memory and experience of the building representatives 

and, in the case of residential units, may not reflect the condition or treatment of the entire 

building.

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. Given the purpose of this 

investigation, the limited amount of locations sampled, and the uncertainty in some of the 

survey results, no attempt was made to correlate survey information with measured 

concentrations of any of the materials. The table in Appendix B provides a summary of 

results from the survey form questions that were most consistently answered.

B. Settled Surface Dust

Settled surface dust samples were analyzed for materials consistent with debris from a 

building collapse. Materials of interest include insulation material (asbestos, synthetic 

vitreous fibers, components of concrete (portlandite, calcite, and crystalline silica) and 

components of other building materials (gypsum, mica, and halite). A detailed summary of 

results is given in Appendix C. To protect the privacy of individuals who allowed 

sampling in their residences and buildings, specific detailed locations are not shown. 

Results of the settled surface dust analysis indicate the composition of settled surface dust 

in lower Manhattan is different from that of the dust analyzed from the comparison areas 

above 59th Street. Although the materials found are consistent with materials expected 

from the World Trade Center collapse, these results cannot determine the actual source of 

the materials present because these materials are common building components and can 

come from other sources in a busy urban area.

1. Fiber Analysis of Settled Surface Dust

All settled surface dust samples were 

analyzed by polarized light microscopy 

(PLM) for fiber type and content. This 

technique distinguishes between asbestos 

fibers, textile fibers, and synthetic vitreous 

fibers (SVF), which include glass wool and 

mineral wool. The results are reported as a 

percent. Because PLM is an optical method, the amount reported is a visual estimation of 

the percent of area viewed. Therefore it is neither strictly a weight or a volume percent. 

Asbestos and SVF, although not 

found in homes in the comparison 

areas above 59th Street, were 

present in the settled surface dust 

in some areas of lower 

Manhattan.
20

These results do provide an indication of the presence of asbestos or SVF in the dust, and 

some idea of relative amount.

In lower Manhattan, asbestos was only detected in settled surface dust in one indoor and 

two outdoor locations by PLM (Figure 8). If asbestos was not seen in the sample or 

reported as <1% by PLM, a second test was done which is more sensitive, transmission 

electron microscopy (TEM). An additional 4 outdoor and 15 indoor locations contained 

asbestos when examined by TEM (Figure 9). Chrysotile asbestos was the only form of 

asbestos identified, either by PLM or TEM, in all settled surface dust samples. In this study 

TEM is primarily used as an indicator of the presence or absence of asbestos. For the PLM 

analysis, values <1% are an indicator of the presence of asbestos because this is the 

detection limit for PLM. For TEM a detection of asbestos is confirmation of its presence. 

Therefore, values <1% and values greater indicate the presence of asbestos. Results shown 

in Table 6 and discussed below refer to all samples positive for asbestos, by either the 

PLM or TEM methods (Figure 10).

Asbestos was found in indoor settled surface dust in 10 of 57 residences sampled in lower 

Manhattan (18%) (Table 6). The settled surface dust in common areas contained asbestos 

in 5 of 26 areas sampled (19%), and asbestos was found in outdoor dust in 6 of 14 areas 

sampled (43%) (Table 6). Asbestos levels ranged from none detected up to 3.4% (the 

highest level was found in an outside sample). However, without surface-loading 

information, the percentage of asbestos present does not allow for characterization of 

potential exposures. No asbestos was found in the comparison homes north of 59th Street. 

Figure 10 depicts the results of analysis of the asbestos content of settled surface dust in 

samples from residences in lower Manhattan.

The SVF results, seen in Table 6, show a broad range of SVF content in the settled surface 

dust from none detected up to 35% in indoor dust samples and as high as 72% outdoors. 

The location and range of SVF found in settled surface dust is shown in Figure 11 for all 

areas sampled in lower Manhattan. SVF was found in indoor dust in 26 of 57 residences 

sampled as analyzed by PLM (46%). The settled surface dust in common areas contained 

SVF in 14 of 26 areas sampled (54%), and SVF was found in outdoor dust 11 of 14 times 

sampled (79%). The majority of SVF detected was glass wool. Only four buildings 

contained mineral wool in settled surface dust, ranging from 1%–7%. Because no surfaceloading information is known, the exact percentage is less informative than its presence. 

No SVF was found in the comparison homes north of 59th Street by PLM analysis. 

Therefore the SVF content of settled surface dust in some areas of lower Manhattan is 

higher than that of the selected comparison areas above 59th Street (Figure 11).

2. Mineral Analysis of Settled Surface Dust

Settled surface dust samples were analyzed for crystalline minerals potentially associated 

with the material from the collapsed World Trade Centers. The results reported here are 

expressed as a mass percent of the dust (weight of minerals per weight of dust). 

Quantification of the minerals in dust is not exact due to variations in particle size and 
21

other methodological interference. Therefore, these data will only be considered 

semiquantitatively and should be considered estimated values, noted by the “J” qualifier.

Quartz, calcite, portlandite, and gypsum were the most abundant minerals detected (see 

Table 7). Mica was detected with less frequency than the other minerals, and generally 

estimated at approximately 0.1%J of the dust. Halite (salt) was also detected at trace 

levels.

Quartz was detected in all 14 outdoor dust 

samples, 21 of the 26 common area samples, 

and only 30 of the 57 samples from 

residences in lower Manhattan. Neither 

cristobalite nor tridymite, other forms of 

crystalline silica, were found in any of the 

settled surface dust samples. For this 

discussion quartz will refer to the alphaquartz form of crystalline silica. Levels of 

quartz were estimated as from 0.05%J to 

31%J in residences, and from 0.03%J to 

25%J in common areas. Estimated quartz 

content in outdoor samples ranged from 1%J 

to 27%J. Because quartz is a common material (i.e., silica sand), finding this mineral in the 

city where there is a lot of concrete building material is not unusual. However, quartz in 

dust from the comparison areas above 59th Street was estimated from nondetect to 1%J in 

the common areas and from nondetect to 2%J in the residences. Figure 16 shows the 

locations where the estimated maximum quartz content in settled surface dust was greater 

than or similar to estimated quartz content in the dust samples from the comparison areas 

above 59th Street. Fifteen residences, six common areas, and 12 outdoor areas had 

estimated quartz levels higher than the associated comparison areas above 59th Street. 

Therefore, quartz was elevated in some indoor areas of lower Manhattan relative to the 

comparison areas above 59th Street. Outdoor dust samples were not taken from the 

comparison areas, due to insufficient amounts of dust. Figures 13-16 compare the indoor 

and outdoor locations in lower Manhattan to the indoor samples above 59th to show the 

relative distribution of the minerals.

Calcite (calcium carbonate) and portlandite (calcium hydroxide) are also components of 

concrete. They occurred with similar frequency in the dust samples and were often colocated with the quartz. Calcite ranged from an estimated 0.8%J to 19%J in outdoor areas, 

and from 0.02%J to 21%J in indoor areas. Portlandite ranged from an estimated 0.07%J to 

6%J in outdoor areas and from 0.04%J to 8%J in indoor areas. In contrast, the maximum 

levels found in indoor comparison areas above 59th Street were 0.9%J calcite and 0.08%J 

portlandite. Figures 13 and 15 show the locations where the estimated calcite and 

portlandite content in settled surface dust was higher than to that estimated in dust samples 

from the comparison areas above 59th Street. For calcite, 13 residence and 9 common area 

samples had estimated levels higher than those found in the comparison areas above 59th 

Street. Similarly for portlandite, 17 residence and 9 common area samples were estimated 

Mineral components of concrete 

(quartz calcite, and portlandite) and 

other building materials (gypsum, 

mica, and halite) in the indoor settled 

surface dust of some areas of lower 

Manhattan were estimated at higher 

percentages than for the comparison 

areas above 59th Street.
22

as higher than values in comparison areas above 59th Street. So although these materials 

are found in urban areas, perhaps due to erosion of concrete, building construction and 

maintenance, the estimated percentages of calcite and portlandite were larger in some 

areas of lower Manhattan relative to the comparison areas above 59th Street (Figures 13 

and 15.)

Gypsum (hydrated calcium sulfate) is a major component of dry wall. Gypsum was found 

in 11 of 14 outdoor settled dust samples at levels estimated as 0.03%J to 27%J. Indoor 

levels of gypsum ranged from an estimated 0.07%J to 20%J in 23 of 26 common areas and 

from 0.05%J to 30%J in 45 of 57 residences. These estimated percentages are higher than 

the estimated maximum of 4%J seen in the comparison areas above 59th Street. Figure 14 

shows the locations where the estimated gypsum content in settled surface dust was higher 

than or similar to the levels in the dust samples from the comparison areas above 59th 

Street. Nine residence and six common area samples had estimated levels higher than 

those found in the comparison areas above 59th Street. Gypsum was elevated in settled 

indoor dust in some areas of lower Manhattan relative to the comparison areas above 

59th Street (Figure 14).

The data can also be evaluated in a nonquantitative manner by just inspecting the frequency 

of detects of mineral in dust for lower Manhattan and the comparison areas. As shown in 

Table 7, the pattern of prevalence for the minerals appears to be similar in both study 

areas. In other words, the minerals were detected in both locations with about the same 

frequency. The data imply that building materials were the source for both areas. This 

source was likely building materials; however, the magnitude of the impact was greater in 

areas closer to the World Trade Center.

3. Alkalinity of Settled Surface Dust

Several of the minerals detected in the settled surface dust samples, such as portlandite, 

can make the dust more alkaline, or raise the pH. Originally, the pH of all of the settled 

surface dust samples was to be determined. However, enough dust for this analysis was 

only available at two locations. Both dust samples were alkaline (pH of 8.6 and 9.8). On 

the pH scale of 0 (acidic) to 14 (alkaline or basic), these values are slightly alkaline. 

Mineral analysis of these two settled surface dust samples estimate levels of calcite 

(15%J, 19%J) and portlandite (6%J, 3%J) were present, respectively. These crystalline 

minerals along with other components of concrete would have contributed to the measured 

alkalinity.

C. Air 

The settled surface dust results discussed previously indicate the materials present in each 

area sampled. Fibers and small particles within the dust may become airborne during daily 

activity or during periods of high activity such as cleaning. Therefore, the settled surface 

dust sample results are an indicator for areas with a potential for airborne contaminants. 
23

Air sampling was conducted to determine the actual levels of fibers, dust, and crystalline 

minerals in the air at the time of settled surface dust sampling. Where feasible, these results 

are correlated to the settled surface dust results.

1. Fibers in Air

Samples for airborne fibers were first analyzed by phase contrast microscopy (PCM) to 

count all fibers present according to the National Institute for Occupational Safety and 

Health (NIOSH) Method 7400 counting rules. Phase contrast microscopy identifies fibers 

based on size and shape, but not the specific type of fiber. Therefore, the fibers seen by 

PCM include asbestos fibers as well as other fibers, such as textiles, fiberglass, and 

cellulose that might be present. Any sample with airborne fibers above the highest PCM 

levels found in the comparison locations was re-analyzed by transmission electron 

microscopy (TEM) and scanning electron microscopy (SEM). The TEM methodology can 

distinguish what types of fibers are in a sample, particularly asbestos fibers. The SEM 

method identifies SVF. Some fibers present in the settled dust of the area may become 

suspended in the air and be present in the air sample.

a. Indoor Air

Fiber levels in air are expressed as the number of fibers in each cubic centimeter (cc) of 

air or fibers per cc (f/cc). Low levels of fibers were found in the comparison areas above 

59thStreet homes, where fiber levels ranged from less than 0.001 f/cc (<0.001 f/cc) to 

0.003 f/cc. Because no asbestos was detected in the settled surface dust of the comparison 

areas above 59th Street, these fibers are not likely to have been asbestos. SEM analysis 

showed they were not SVF. Figure 7 shows all airborne fiber levels determined by PCM in 

the lower Manhattan area with respect to the fiber levels found in the comparison areas 

above 59th Street. These data represent all fibers found according to the analytical method 

used (NIOSH 7400) and are not specific to asbestos or SVF.

The majority of the lower Manhattan air samples from indoor areas without asbestos in the

dust were within the range of fibers found in the comparison areas above 59th Street 

(<0.001 to 0.003 f/cc). Six of these air samples (from 3 common areas and 3 residences) 

had higher levels of fibers in air than the comparison areas above 59th Street (Table 8). 

Four of these areas had measurable levels of SVF in the settled surface dust. All six-air 

samples were re-analyzed by TEM to determine if the fibers present included asbestos 

fibers. Asbestos fibers were not found in these six air samples (Table 8). A third analysis 

was done by SEM to determine if SVF fibers were present in those air samples from areas 

with SVF in the settled surface dust. SVF fibers were found in three of these air samples at 

concentrations from 0.000037 f/cc to 0.000255 f/cc. Although SEM is a more sensitive 

method, detecting thinner fibers than PCM, reported SVF levels were well below the PCM 

method detection limit of 0.001f/cc. SVF fiber concentrations in the comparison areas 

above 59th Street ranged from none detected to 0.000087 f/cc. Although air samples from 

comparison areas above 59th Street were not re-analyzed by TEM, no asbestos fibers were 

noted on the subsequent SEM analysis for SVF. Therefore the six air samples that had total 
24

fiber counts greater than comparison areas above 59th Street were not elevated due to 

either asbestos or SVF fibers.

There were 15 out of the 83 (18%) indoor areas in lower Manhattan with measurable 

asbestos in the settled surface dust, 10 residences and 5 common areas (Table 9). Nine of 

these residences were sampled aggressively (the air exhaust of the vacuum used for settled 

dust sampling was used to stir up all dust into the air before an air sample was taken). Four 

of these aggressively sampled residences had measurable fiber levels in air ranging from 

0.001 f/cc to 0.003 f/cc. One residence was occupied and could not be aggressively 

sampled. Air sampling at that location indicated <0.001 f/cc by PCM analysis. Because the 

levels found were within the range measured in the comparison areas above 59th Street, no 

TEM or SEM re-analysis was performed on these air samples. Therefore the composition 

of these fibers is unknown (i.e., asbestos, SVF, cellulose).

None of the common areas were aggressively sampled because all of these areas were 

open to the public. Of the five common areas with some asbestos in the dust, three had 

measurable levels of fiber in the air ranging from 0.001 f/cc to 0.002 f/cc. One area in 

building 5 where there was not enough settled surface dust to sample had an airborne fiber

count of 0.002 f/cc. No TEM or SEM re-analysis was performed on these air samples, and 

the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

b. Outdoor Air

Six of the 14 lower Manhattan outdoor locations sampled had detectable levels of asbestos 

in the settled surface dust, indicating a potential in these locations for asbestos fibers to 

become airborne. Air sampling indicates three of the locations did not have detectable 

fibers in the air (Table 9). The air samples from buildings 1, 2, and 5 did have fibers 

detected at levels from 0.001 f/cc to 0.003 f/cc. Of the 15 locations where no settled 

surface dust samples were taken, the majority of the results showed <0.001 f/cc in the air, 

with only 4 samples reported at the detection limit of 0.001 f/cc. Because the levels found 

were within the range measured in the comparison areas above 59th Street, no TEM or 

SEM re-analysis was performed on these air samples, and the composition of these fibers 

is unknown (i.e., asbestos, SVF, cellulose).

2. Minerals in Air

Air samples of different particulate sizes, representing inhalable (PM100), thoracic 

(PM10), and respirable (PM4 and PM2.5) fractions were collected in selected building 

locations. Not all size fractions were collected at every location. The samples were 

analyzed by XRD for the same crystalline minerals seen in the settled surface dust samples. 

Each of the four size fractions was collected with a separate sampling device. The PM100 

fraction collected particles with an aerodynamic diameter of 100 microns and lower. The 

PM10 fraction collected particles with an aerodynamic diameter of 10 microns and lower 

and so on. The results reported here are expressed as the mass of mineral per unit volume 

of air or micrograms per cubic meter of air (μg/m3). Quantification of the minerals is not 

exact due to variations in particle size as compared to the particle size used in the standard 
25

curve and other methodological interference. Therefore, these data will only be considered 

semiquantitative and should be treated as estimated values, noted by the “J” qualifier.

Due to changes in sample volume, the detection limit of minerals in each fraction varied, 

allowing lower concentrations to be recorded in the PM10 and PM100 fractions compared 

to the PM4 fraction. Care must be taken when comparing results between fractions for this 

reason. Additionally, although the PM4 fraction should be a subset of the PM10 and 

PM100 fractions, PM4 results are sometimes higher than PM10 or PM100 from the same 

location. Therefore, due to uncertainties in the quantification and general quality 

assurance/quality control concerns, data will not be associated to a specific building 

sampling location or correlated between size fractions at the same location.

The comparison air samples, taken in areas above 59th Street, contained no quartz, 

cristobalite, tridymite, calcite, portlandite, mica, or halite above method detection limits 

(Table 11). Gypsum was found at least once in all size fractions collected in the 

comparison areas above 59th Street. Gypsum concentrations were estimated at 3 μg/m3J 

(PM2.5), 5 μg/m3J (PM4), 3 μg/m3J (PM10), and 3 μg/m3J (PM100) (Table 11).

All of the minerals found in the settled surface dust were seen in at least one air sample 

from lower Manhattan (Table 11). Quartz, calcite, portlandite, and gypsum were detected 

at similar frequencies in each of the larger size fractions, PM100, PM10, and PM 4. Table 

11 shows the frequency of detection and the range of estimated values for each size fraction 

sampled. Quartz and gypsum were each detected once in the PM 2.5 fraction. The PM 2.5 

size fraction was only collected toward the end of the project, and there are fewer samples 

for this size fraction.

Approximate quartz levels in air ranged from 

4 μg/m3–19 μg/m3J in the respirable fraction (PM4), 

3 μg/m3–12 μg/m3J in the thoracic fraction (PM10) 

and 3 μg/m3–13 μg/m3J in the inhalable fraction 

(PM100). Detection frequencies were similar in 

these fractions at 11%, 10%, and 14% respectively. 

However, quartz was only seen in one of the PM2.5 

samples (3%) at an estimated 3 μg/m3

J. Cristobalite, 

a different crystalline form of crystalline silica, was 

found in one lower Manhattan air sample at 

15 μg/m3J in the PM100 fraction. Cristobalite was not seen in any other sample, either air 

or settled surface dust. Across the size fractions, quartz was detected in air samples taken 

in lower Manhattan; it was not detected in the comparison areas above 59th Street. 

Therefore, the estimated airborne levels of quartz appear to be higher in some air samples 

from lower Manhattan than the chosen comparison areas above 59th Street.

Similar observations can be seen in the results for calcite and portlandite. Calcite and 

portlandite occur at a similar frequency to quartz (Table 11) and tend to be present in the 

same air samples (Appendix C.) Both minerals are present in PM4, PM10, and PM100 size 

fractions. Calcite was estimated at 3 μg/m3J–14 μg/m3J and portlandite at 14 μg/m3J–95 

Estimated levels of minerals in 

air, including quartz, calcite, 

gypsum, and portlandite, appear 

higher in some areas of lower 

Manhattan than in the 

comparison areas above 59th 

Street.
26

μg/m3J in inhalable dust. Mica and halite are not seen with the same frequency, but are 

detected in several air samples from lower Manhattan. Calcite, portlandite, mica, and 

halite are all detected in air samples taken in lower Manhattan, but not in air samples from 

the comparison areas above 59th Street (Table 11). Therefore, the airborne levels of 

calcite, portlandite, mica and halite appear to be higher in some air samples from lower 

Manhattan than in the samples from the comparison areas above 59th Street.

Gypsum was the most common mineral detected in air samples from lower Manhattan for 

all size fractions and was detected in 40 out of 114 respirable fraction (PM4) air samples 

at levels ranging from approximately 4 μg/m3J–15 μg/m3J. Gypsum was estimated at 

3 μg/m3J–14 μg/m3J and detected less frequently in the PM10 (33 of 105) and PM100 (24 

of 101) size fractions, even though the detection limits for these fractions were lower. 

Gypsum was found in one of the PM2.5 samples, at approximately 3 μg/m3J. Across the 

size fractions, gypsum was detected in air samples taken in lower Manhattan at higher 

estimated levels than air samples taken from the comparison areas above 59th Street (up to 

5 μg/m3J). Therefore, the airborne levels of gypsum seem to be higher in some air samples 

from lower Manhattan than the chosen comparison areas above 59th Street.

DISCUSSION

This section of the report will provide a more in-depth review of where the various 

materials were detected. In addition, the public health concerns potentially associated with 

these materials is also presented.

A. Discussion of Results

Settled surface dust samples obtained from lower Manhattan as part of this investigation 

contained materials consistent with debris from a building collapse. Both indoor and 

outdoor settled surface dust samples contained some amount of insulation material 

(asbestos, glass wool, and mineral wool), components of concrete (portlandite, calcite, 

and quartz), and components of other building materials (gypsum, mica, and halite). These 

materials were not present at the same levels in the four buildings above 59th Street 

sampled for comparison.

Asbestos levels in dust in the lower Manhattan area, ranging from <1% to 3.4%, were 

consistent with samples taken of outdoor material by EPA after the WTC collapse. SVF 

levels in the settled surface dust in lower Manhattan were higher than in the comparison 

areas above 59th Street, ranging from 1% to 72%. No data were available for SVF in 

lower Manhattan prior to this investigation. Analysis of archived dust samples collected 

after the WTC collapse by NIOSH, confirms the presence of SVF in bulk samples taken in 

lower Manhattan.

The minerals found in settled surface dust from residential buildings in lower Manhattan 

were consistent with minerals reported by the United States Geological Survey (USGS) for 

outdoor settled surface dust across lower Manhattan after the WTC collapse (9). 

Thirty-three dust, two concrete, and two steel insulation samples were analyzed by USGS, 
27

including two from an indoor area. Quartz, calcite, and gypsum were reported for all of 

these samples. Each of these was occasionally reported as a major constituent of the 

material, i.e., estimated at 20% or higher. Twenty-six of these samples contained mica, 

usually estimated as trace or less than 5% of the material. Portlandite was only noted in 

two samples at trace levels, including the one indoor sample analyzed.

1. Association of Asbestos and Synthetic Vitreous Fibers

Based upon the sampling results, it appears that SVF is likely to be found in settled surface

dust whenever asbestos is detected in the settled surface dust. All of the six outdoor and 

five common areas that had asbestos in settled surface dust also had SVF in the settled 

surface dust (Table 9). Of the ten residences that contained asbestos in settled surface dust, 

a little more than half also contained SVF. However, this does not hold true in areas 

without asbestos, where the absence of asbestos does not indicate an absence of SVF. Of 

the eight outdoor areas without asbestos in the settled surface dust, three contained SVF. 

Similarly, SVF was found in approximately 25% of the common areas and in 

approximately 36% of the residences without asbestos in the dust. Although the presence of 

asbestos in the dust seems to correspond to SVF, the absence of asbestos does not predict 

or correspond to a presence or absence of SVF in settled surface dust, in either indoor or 

outdoor areas of lower Manhattan.

2. Association of Asbestos and Synthetic Vitreous Fiber Levels Outside of and Within 

 a Building

Outdoor settled surface dust was collected at 14 buildings in lower Manhattan. One 

purpose for collecting outdoor dust was to determine if the contents of the outdoor dust at a 

location would reflect the type of indoor dust. In the case of fibers, there is little 

correlation in the indoor and outdoor dust composition. High levels of outdoor SVF are 

associated with both high and low indoor levels. The presence or absence of asbestos in 

settled surface dust shows a similar lack of correlation. The outdoor settled surface dust 

samples do not correspond with indoor dust composition for either group of fibers. This 

lack of association could, in part, be due to whether and how frequent interiors and 

exteriors had been cleaned.

In contrast, indoor levels of fibers in settled surface dust did seem to correspond within a 

building. Buildings with elevated SVF levels in the common area tended to have elevated 

levels in the residences. A similar pattern was seen between the two residences sampled in 

the same building. For example, SVF was often found in both residences sampled within 

the same building, or was absent in both residences. Within this limited data set, fiber 

levels in one area of a building seem to weakly correspond with fiber levels in other areas 

of the same building. However, none of these data represent total dust loading, only the 

relative amount of fibers within the dust.
28

3. Occurrence of Crystalline Minerals

Indoor areas that have elevated levels of quartz in settled surface dust appear to also have 

elevated levels of calcite, portlandite, and gypsum (see Figure 10). Additionally, these four 

minerals appear together in all outdoor samples with only minor exceptions. Although only 

14 of the 30 buildings had samples taken of outdoor dust, there does seem to be a 

correlation between elevated outdoor and indoor levels of quartz, gypsum, and the other 

minerals. It is unknown if this would be seen in outdoor areas above 59th Street for 

comparison, as not enough outdoor dust was available for analysis.

Most elevated quartz and gypsum levels indoors were found in the first ten buildings 

sampled during the first 5 days of the project (with the exception of 14% quartz in the 

common area of building 22). Although many of these buildings were closer to the WTC 

site, location may not be the only factor contributing to higher mineral levels in the dust. 

Other buildings sampled in these areas later (e.g., 13, 14, and 28) did not have elevated 

levels of minerals. Many factors may contribute to this finding including whether the area 

was cleaned (indoors, outdoors), the cleaning method used, the time since the last cleaning, 

and the amount of dust that was initially in the area. It is not clear which factors contributed 

to variation in mineral levels by building.

Within a building, levels of quartz, calcite, and portlandite tended to be similar, and in 

some cases showed a similar profile in areas with elevated quartz (see Figures 13, 15, and 

16). In general, where quartz was greater than 5%, calcite and portlandite were also 

present, but as smaller proportions of the dust. Gypsum, although often present with the 

other minerals, varied from being the most abundant to the least abundant in the dust.

4. Buildings Impacted by Asbestos, Synthetic Vitreous Fibers, and Crystalline 

Minerals

There was no clear pattern of which buildings were impacted by asbestos, SVF, and 

crystalline minerals. Figure 17 shows the approximate locations of the buildings and the 

level of contaminants in settled surface dust that were above or below the levels found in 

the comparison areas. The data are summarized and presented to indicate the indoor areas 

within a building with higher levels of a material in settled surface dust than was found in 

the comparison areas above 59th Street (Table 12). In this table, quartz was considered 

representative of the two other minerals associated with concrete, portlandite and calcite.

In 6 of the 29 buildings (approximately 21%) sampled in lower Manhattan, concentrations 

of these materials were not detected at levels higher than the levels in the comparison 

buildings above 59th Street. These six buildings tend to be among the buildings farthest 

from the World Trade Center and not located along what appear to be major streets or 

intersections. Map 17 shows the approximate locations of the buildings and the level of 

contaminants in settled surface dust that were above or below the levels found in the 

comparison areas.
29

Twenty-three buildings (approximately 79%) had levels of at least one of these materials 

in the dust at levels higher than the maximum found in the comparison buildings. Four of 

these buildings (buildings 4, 5, 6, and 9) contained all four materials above levels seen in 

the comparison areas above 59th Street in at least one indoor sample (Table 7). Seven of 

the 23 buildings were only impacted by SVF in indoor areas (buildings 13, 14, 17, 18, 25, 

26, and 28). One building was only impacted by asbestos (building 11). The remaining 11 

buildings were impacted by some combination of fibers and minerals. No clear pattern 

emerges in terms of which fibers or minerals occurred in the indoor dust of a building. 

Three of these building had only the two fiber types present (buildings 15, 24, and 27). One 

of these building had only the two minerals present (building 8).

The limited number of buildings sampled and the limited number of indoor locations that 

were sampled make it difficult to draw conclusions about the relationship of geographical 

location and the number of different materials found in the dust above the levels found in 

the comparison locations. However, buildings close to the World Trade Center tend to 

have a greater number of these materials found.

5. Significance of Minerals and Fibers in the Settled Surface Dust

The results previously discussed indicate minerals, asbestos, and 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 daily 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 
30

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 respirable 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 were samples taken which showed fibers by PCM, which were 

not re-analyzed. Any of these air samples, especially those taken in areas with asbestos or 

SVF in the dust, may have some of these fibers as part of the PCM fiber count. Generally, 

the levels of dust and air did not indicate a consistent pattern at different locations. It was 

not possible to conduct a more accurate correlation analysis between asbestos and SVF 

material in settled surface dust and fibers in air because the majority of air samples were 

not analyzed specifically for asbestos or SVF (i.e., TEM or SEM analysis). The limited 

data gathered during this investigation does not support nor refute the assumption that all 

the fibers in the air samples will be asbestos or SVF even when asbestos was found in 

dust.

B. Public Health Evaluation

The potential for health effects is possible after exposures to certain materials. An 

exposure to a material occurs when it comes into contact with or is taken into our bodies. 

The route of exposure is the method by which a material comes into contact with the body 

(e.g., dermal contact, inhalation, or ingestion). The nature of the health effect will depend 

on the material involved, how it comes into contact with the body, the amount of material 

(exposure level), the duration of the exposure, resultant dose, and the susceptibility of the 

individual (e.g., pre-existing health conditions may make an individual more sensitive to a 

contaminant). 

Initially, screening values were established and listed in the project-sampling plan. These 

screening values were established to provide a guideline for evaluating the data as it was 

collected for any indication of a hazard requiring immediate attention, and to ensure the 

proper analytical detection limit to support a chronic health evaluation. These screening 

values were not used in this report because this public health evaluation is specific to the 

levels of materials found in the study area.
31

Because levels of asbestos, SVF, and some crystalline minerals are elevated in the settled 

surface dust of some buildings in lower Manhattan, individuals may be exposed to those 

materials in their homes, out of doors, or at work either by direct contact or by inhalation 

when the dust is disturbed and suspended in the air. Depending on the environment, one or 

all of these materials may be present in the dust of an area.

1. Sensitive Populations

Sensitive populations are individuals who may experience greater responses when 

exposed to a material than normally predicted. This sensitivity may be due to life stage, 

pre-existing medical or exposure conditions, or genetic susceptibility.

Children are considered a sensitive population for several reasons. The first consideration 

is the potential for greater exposure than adults. With a lower body weight, and higher 

relative ventilation rate, children have higher doses than adults given exposure to the same 

levels of materials in air, food, or drinking water. For biopersistent materials, such as 

some of the minerals discussed previously, childhood exposures present a greater lifetime 

risk due to longer residence time in the lung. This is demonstrated for asbestos where an 

exposure with onset at 1-year old presents a greater risk than an exposure at age 18 (10). 

Finally, because they are shorter than adults, children breathe air that is closer to the 

ground, and they may play in contaminated areas, creating situations where they are 

impacted more by materials in soil or dust.

Children and adults with pre-existing medical conditions may be more susceptible. Many 

of the materials found in the areas sampled have irritant effects on skin, mucous 

membranes, and the respiratory tract. Individuals with pre-existing allergic and 

cardiopulmonary diseases may be more sensitive to the effects of exposure to this dust. 

One of the most clinically important and frequent responses of the airways to dust and 

irritant exposures is bronchoconstriction. Therefore, individuals with pre-existing asthma 

are much more likely to develop bronchoconstriction in response to exposure to dust 

particles, fibers, and irritants.

Obstructive lung disease and other respiratory and cardiopulmonary disorders are factors 

for increased sensitivity. Any individuals in lower Manhattan who received a large dose of 

dust during or immediately following the WTC collapse may also be more sensitive. 

Anyone who has been experiencing respiratory symptoms since the collapse should consult 

their physician for proper treatment.

Individuals who smoke are at greater risk. Smoking can reduce lung function and may cause 

pulmonary disease that would make individuals more sensitive. Additionally, smoking has 

been shown to synergistically increase the risk of developing lung cancer from asbestos 

exposures. Smoking also increases the risk of developing lung cancer in workers exposed 

to crystalline silica (e.g., quartz).
32

2. Soluble Minerals: Gypsum, Portlandite, and Calcite

The potential health effects of gypsum (hydrated calcium sulfate), 

portlandite (calcium hydroxide), and calcite (calcium carbonate) 

are similar as these minerals are similar chemically and 

physically. All three minerals are crystalline in form and soluble 

(11,12). Because these minerals are soluble in 

body fluid, they are easily cleared from the respiratory tract and 

lungs when inhaled (13,14,15). Therefore, no long-term respiratory effects have been 

observed, even at the very high exposures that occur during the mining and processing of 

these minerals (16,17).

Calcite, and portlandite increase the alkalinity of a fluid. Therefore, when these materials 

come into contact with tissue, they can cause irritation of skin and mucous membranes due 

to increased alkalinity. Any anhydrous gypsum in settled dust would be hygroscopic, 

which would be drying and irritating to the skin and eyes. Similarly, inhaled material may 

irritate or burn the respiratory tract (nose, throat, and lungs). The signs of an inflammatory 

response include redness, swelling, heat, and pain. Reaction to a skin irritant usually 

occurs at the point of contact between the skin and the substance. Eye irritants can cause 

redness, tearing, and itching of the eyes. Respiratory irritants can affect the nose, throat, 

and lungs. They may cause an itchy, watery nose, a scratchy or sore throat, coughing, chest 

tightness, wheezing, or difficulty breathing. All of these irritant effects are generally 

temporary and will begin to resolve once exposures cease.

Occupational exposure guidelines (NIOSH) and standards (OSHA) for these minerals 

were developed to prevent these irritant symptoms in most workers for a 40-hour 

workweek exposure (13,14,15). Although no guidelines or standards are available for skin 

contact or residential exposures, air exposure levels are established for both total and 

respirable minerals in air (see the following table). The airborne mineral levels measured 

in lower Manhattan are orders of magnitude below these occupational values. Although the 

occupational standards do not account for sensitive individuals or for extended periods of 

exposure, they provide a point of comparison. The levels of minerals seen in airborne dust 

of lower Manhattan are not at the levels known to be irritating to healthy adult workers. 

However, it is possible that sensitive individuals may feel some irritation. Additionally, 

direct contact with the dust—or shorter periods of higher air concentrations caused by 

disturbing the dust—may result in more irritation than would be predicted by the reported 

airborne mineral levels.

Although possible skin, eye, 

and respiratory tract irritants,

the soluble minerals gypsum, 

portlandite, and calcite do not 

pose any hazard for long-term 

health effects.
33

Mineral NIOSH REL (μg/m3) OSHA PEL (μg/m3)

Maximum Estimated Value 

in Lower Manhattan (μg/m3)

Gypsum 10,000 (total)

5,000 (resp)

15,000 (total)

5,000 (resp)

14J (PM100)

15J (PM4)

Portlandite 5,000 15,000 (total)

5,000 (resp)

95J (PM100)

84J (PM4)

Calcite 10,000 (total)

5,000 (resp)

15,000 (total)

5,000 (resp)

14J (PM100)

10J (PM 4)

NIOSH = National Institute for Occupational Safety and Health, Centers for Disease 

 Control and Prevention

REL = recommended exposure level/limit

OSHA = Occupational Safety and Health Administration

PEL = permissible exposure limit.

μg/m3 = microgram of mineral per cubic meter of air

total = all airborne particles (could include particles >100 micrometers)

resp = respirable fraction (PM4)

3. Mica

Mica is a group of water-insoluble silicate minerals (18). The mica detected in these dust 

and air samples of lower Manhattan was muscovite. Mica has been shown to cause 

pneumoconiosis in workers exposed to high levels during mining and processing 

operations (19,20). Although workers may have also been exposed to quartz in some of 

these studies, pneumoconiosis in workers with only mica exposures has been documented. 

(21,22)

Respirable mica particles that deposit in the deep lung may be cleared slowly due to the 

relative insolubility of the mineral. Over time, the presence of the mineral will irritate 

the lung tissue, generate immune response, and result in scarring or fibrosis (23,24). The 

magnitude of this response is believed to be a function of both the dose and duration of 

exposure. The current worker standard set at 3,000 μg/m3 is a level at which mild 

pneumoconiosis was seen in some workers only after extended exposure (18 years).

The airborne levels of mica seen in lower Manhattan 

with an estimated maximum of 43 μg/m3J in 

respirable dust are well below levels of mica that 

are associated with the development of 

pneumoconiosis in workers (25). Although 

disturbing settled surface dust might generate shortterm exposures above the measured values, it is the 

cumulative exposure that is believed to predict 

health effects (23). Given the low airborne levels of 

mica seen in lower Manhattan and the low frequency 

of detection in both air and settled surface dust 

samples, no health effects are expected from mica 

exposure alone.

Mica and halite, although 

elevated in lower Manhattan 

relative to the comparison areas 

above 59th Street, are not likely 

to contribute to any adverse 

health effects.
34

4. Halite

Halite is simply sodium chloride, or rock salt (18). This crystalline form of the salt will 

readily dissolve in the body and is not expected to have any adverse health effects. 

Although large changes in salinity can disrupt tissues, the trace amounts of halite and the 

low frequency of detection do not indicate any potential health concern.

5. Crystalline Silica (Quartz and Cristobalite)

Silica is chemically inert for the most part, so it is the physical form of silica that imparts 

its toxicity. Small crystals of silica may be deposited in lung tissue. Once deposited, the 

crystals remain and fibrogenic lesions may appear over time, damaging the lung tissue and 

reducing lung capacity (26). Silica has been demonstrated to be a pulmonary toxin linked 

both to silicosis (a fibrotic lung disease) and lung cancer (27,28,29,30). These findings are 

supported by both human and animal studies. Chronic silica exposure may contribute to 

lung cancer; emphysema; obstructive airway, etiology, immune, or connective tissue 

disease; and lymph node fibrosis (27,30,31,32,33).

a. Silicosis

Generally silicosis is seen after years of high-level occupational exposures, although it can 

result from short-term acute exposure (26,30). It is not known if chronic ambient 

environmental exposure contributes to silicosis (26). Because the lung damage is 

proportional to the total amount of silica deposited in the lung, current evaluations are 

based on a measure of cumulative exposure of air concentration over work-years of 

exposure (28,34,35).

Exposures of less than 1 milligram per cubic meter 1 (mg/m3) of air work-year

∗

of exposure 

are believed to not result in significant incidence of silicosis in workers (28,34,35). The 

peak respirable quartz level estimated in lower Manhattan of 19 μg/m3J would be 

 

∗ Cumulative exposure is expressed as a constant air concentration over a specified period of time. If a worker is 

exposed to a constant concentration of 1 mg/m3 of quartz throughout the workday, for an entire year, that is equivalent 

to 1 (mg/m3) work-year. (One milligram per cubic meter of air is 1 mg/m3).

Short-term exposures to quartz, even for a continuous year of exposure 

at the highest estimated air concentration, is not expected to result in 

any adverse health effects.

Assuming worst-case theoretical assumptions, the estimated quartz 

levels measured cannot rule out adverse health effects from chronic 

exposures (i.e., 30 years). For individuals who conduct frequent cleaning 

of their residences, as recommended in this report, or participate in the 

U.S. Environmental Protection Agency cleaning/sampling program, it is 

unlikely that their exposure would resemble these worst-case conditions.
35

equivalent to 0.08 (mg/m3)-work year.† Therefore, at this measurement even an entire year 

of exposure 24 hours a day 7 days a week would not be expected to result in silicosis when 

compared to work environments known to result in silicosis.‡

b. Lung Cancer

The International Agency for Research on Cancer (IARC) has determined that there is 

sufficient evidence that crystalline silica in the form of quartz or cristobalite is 

carcinogenic in humans (28). The IARC cites only limited evidence for the carcinogenic 

potential of tridymite from animal studies and inadequate evidence in either humans or 

animals to classify amorphous silica. Respirable crystalline silica is listed as a known 

human carcinogen in the National Toxicology Program’s ninth report to Congress (27).

Although the exact mechanism for silica-induced lung cancer is not known, it is believed 

cancer incidence is linked to the development of other silica-induced lung disease (34). It 

is possible the mechanisms involved in the development of silicosis are linked to the 

carcinogenic process through the production of reactive oxygen species and tissue 

responses to immune signals and fibrotic changes (36,37). Some researchers have 

developed dose cancer risk estimates from epidemiologic studies by building off risk 

estimates for silicosis (34,38,39). A risk assessment produced for both silicosis and lung 

cancer on the basis of crystalline silica exposures reviews major studies and proposes that 

lung cancer incidence may be expected to increase by 14% for each additional 1 (mg/m3) 

work-year exposure above the baseline of 1 (mg/m3) work-year exposure (36).∗

The maximum estimated detection of quartz (crystalline silica) in air in lower Manhattan 

was 19 μg/m3J. Using the above risk estimates, the cumulative exposure for 1-year 

continuous exposure 0.08 (mg/m3) work-year poses negligible increased cancer risk.

Although there are uncertainties in this evaluation, current scientific opinion would 

indicate short-term exposures to the measured quartz levels do not pose a health hazard.†

If the highest measured airborne levels are representative of long-term conditions, the 

cumulative exposure for a continuous 30-year residence would exceed the 1 (mg/m3) workyear cumulative exposure which is believed to be the departure point for adverse effects 

 

† In order to compare a continuous residential exposure to a workday exposure, the estimated air level was adjusted to 

be comparable to a shorter workday exposure across the entire year.

‡ It should be noted that children might be at slightly higher risk than adults in sensitive populations. However, the 

estimated 0.08 (mg/m3) work-year exposure is significantly below the departure threshold of 1 mg/m3 per work-year 

exposure, and therefore no adverse effects would be expected.

∗ This estimate was derived by looking at cancer incidence studies and by relating the incidence of lung cancer to 

silicosis risk estimates. Both methods provided similar risk estimates. However it should be noted other authors caution 

about directly linking silicosis and lung cancer risk estimates (39).

† There are many uncertainties about whether this risk would be realized. The first is that even though the risk of cancer 

is not linear, the risk estimates treat it as linear (36). Therefore there may be an overestimate of risk at low exposures 

compared with the studied populations. The air levels of silica we are examining here are well below those studied in 

worker populations; therefore even this small increased risk may be overestimated. Conversely, the studied populations 

were adult workers. So risk estimates based on these studies may underestimate risks to children and to adults with 

respiratory disorders.
36

for both silicosis and lung cancer. Therefore these data cannot rule out the potential for 

long-term risk. However, the highest airborne level measured during this study is not 

necessarily representative of long-term exposure. In addition, the XRD analysis for quartz 

in air is semiquantitative (i.e., an estimated value). This adds additional uncertainty to the 

risk estimation. As presented in the discussion section of this report, it is expected that the 

ongoing cleaning of lower Manhattan and natural dispersion should reduce these materials 

over time, thus reducing long-term risk. Therefore cleaning should be continued and levels 

of respirable crystalline silica monitored, until the data demonstrate that long-term risk of 

adverse health effects is minimal.

6. Synthetic Vitreous Fibers

The term synthetic vitreous fibers (SVF) refers to several types of manufactured vitreous 

fibers: glass wool, mineral wool, and refractory ceramic fibers (RCF) (41,42). Because 

RCF was not found during this investigation, its health effects are not discussed. The types 

of SVF found in settled surface dust, glass wool and mineral wool, are primarily skin and 

upper respiratory tract irritants. Although some data do indicate a potential for pulmonary 

effects, no adverse effects on the lung are expected from the levels measured in this 

investigation.

a. Irritant Effects

The primary short-term and acute health effects 

of SVF are skin, upper respiratory tract, and eye 

irritation (42). It is the physical shape and size of 

the SVF fibers that cause irritation, generally 

fibers more than 5 microns in diameter cause 

skin irritation (41,43,44). The affected area may 

itch and a rash may form. These symptoms 

subside as exposure is ended, as the fibers 

slowly work themselves out of the affected tissue.

Upper respiratory tract irritation due to inhaled 

fibers has been reported when fiber concentrations 

were greater than 1 f/cc in air (41,42,45).

Generally this type of irritation has been observed in individuals who are manufacturing 

and installing SVF insulation materials. Although the settled surface dust results indicate 

SVF is present in many areas of lower Manhattan, total dust loading is not known. Because 

these irritant health effects would be due to the total amount of SVF contact exposure, dust 

loading as well as activity levels would influence whether a particular environment was 

irritating. Extremely low levels were detected in the air samples analyzed via SEM. In the 

PCM analysis, even if all of the fibers counted are assumed to be SVF, the detected 

maximum value of 0.003 f/cc is well below the documented level of irritation. These data 

indicate that SVF is present at elevated levels in settled surface dust and may be an irritant 

under certain conditions, or to sensitive individuals. No long-term health effects are 

No long-term health effects are 

expected from the skin and eye 

irritation that may have occurred 

because of exposure to synthetic 

vitreous fibers.

No adverse pulmonary health effects 

are expected from the levels of 

airborne synthetic vitreous fibers 

measured in this investigation.
37

expected from the skin, eye, or upper respiratory tract irritation related to the SVF 

exposure.

b. Pulmonary Effects

SVF less than 3 microns in diameter are respirable and available to enter and deposit in 

the pulmonary regions of the lung (41). Clearance of these fibers from the lung will be 

determined by fiber solubility and length (41,42). Fibers cleared from the lung have less 

potential to create long-term health effects.∗ Although some animal studies have 

demonstrated both fibrotic and carcinogenic potential for fibrous glass and mineral wools 

(41,42,46), more recent studies do not fully support this finding.† Epidemiologic studies on 

workers exposed to fibrous glass do not provide consistent evidence of pulmonary effects, 

although some effects were noted (42,47). Similarly, when assessing deaths due to lung 

cancer in workers exposed to glass wool, studies do not provide strong evidence for 

increased risk of cancer deaths attributable to glass wool fiber exposures.

The carcinogenic potential of fiberglass has been reviewed by several agencies. The IARC 

originally classified both glass and mineral wool fibers as Group 2B carcinogens, possibly 

carcinogenic to humans, based on animal studies (50). Similarly these materials were 

classified as carcinogens by the National Toxicology program and the American 

Conference of Governmental Industrial Hygienists (41,49). However a review of the 

carcinogenic potential of these fibers by IARC in 2001, which takes into account updated 

human studies, animal inhalation studies, and mechanistic studies, recommends a change in 

this classification. The IARC has announced that the recent monograph designates both 

glass and mineral wool as Group 3, unclassifiable as to carcinogenicity in humans, because 

of inadequate evidence of carcinogenicity in humans and the relatively low biopersistence 

of the materials (50).

Although both glass wool and mineral wool have been found at elevated levels in the 

settled surface dust in lower Manhattan, airborne levels are extremely low, and well 

below a level associated with the worker exposures reviewed in this report. No adverse 

pulmonary health effects are expected from the airborne SVF levels measured in this 

investigation.

 

∗ Less soluble materials have a longer residence time in the lung and therefore have a greater potential to contribute to 

tissue damage or malignant disease. Within SVF types, glass fibers and slag wool are considered the most soluble, and 

therefore least toxic. Mineral wool is less soluble than glass wool. Fibers longer than approximately 15 microns, the 

diameter of a macrophage, are also cleared less efficiently, leading to a greater potential for adverse effects (26).

† Early studies often relied upon injection and implantation studies, which may not accurately predict a pulmonary 

response from inhalation exposures. A review of inhalation studies indicates that glass wool did not cause pulmonary 

fibrosis or lung cancer in these animal studies (47). A recent study by Hesterberg indicates no increase in pulmonary 

fibrosis or lung cancer even at doses of 222 f/cc, although cancer incidence in control animals was considered high (51).
38

7. Asbestos

Asbestos refers to a group of natural fibrous silicate minerals of various structures (18). 

Used primarily for its fire resistant properties and as an insulation material during the 

1900s, asbestos is now known to cause pulmonary damage, lung cancer, and mesothelioma. 

Asbestos fibers less than 2 microns in diameter and less than 5 microns in length with a 3:1 

aspect ratio may enter and deposit in the alveolar and pleural regions of the lung (10). 

Material that is not cleared by the normal processes of the lung will remain, resulting in 

possible damaged tissue, fibrotic lesions, and cancer (10,52–54). Fibers may also migrate 

from the lung to the pleural lining, causing mesothelioma. This discussion will focus on the 

most studied health effects, asbestosis and cancer. It should be noted that the chrysotile 

asbestos found in settled surface dust during this investigation is believed to be cleared 

from lungs to a greater degree than other forms of asbestos (10). Therefore the following 

review, which considers all forms of asbestos, would be conservative for chrysotile 

asbestos exposures.

a. Asbestosis

Asbestosis is similar to other mineral pneumoconiosis of the lung. Fibers are deposited in 

the lung and remain due to their insoluble nature and the inability of lung macrophages to 

engulf and remove longer fibers (>5 microns in length) (10,54). These fibers can create 

localized tissue damage, stimulate the immune system, and create a scarring of the lung.

Asbestosis has been observed in workers exposed over several years to levels much 

higher than seen environmentally. It is believed the cumulative exposure to asbestos 

correlates to the development of asbestosis, and some cases of asbestosis have been 

reported with only a brief high exposure documented (55). Because cumulative asbestos 

exposure is believed to be the appropriate metric for assessing asbestos health effects, it is 

possible long-term, continuous low-level exposures could contribute to asbestosis. Recent 

studies of a population exposed to tremolite asbestos in Libby, Montana, do indicate 

increased pleural anomalies, consistent with asbestosis, for individuals who were not 

exposed occupationally. Individuals who lived with plant workers or those who had 

contact with vermiculite piles containing tremolite had increased odds ratios for these 

anomalies (56). 

Although asbestos is present in some settled surface dust in lower Manhattan, aggressive 

sampling produced a maximum level of 0.003 f/cc (PCM). This level is not high enough to 

result in asbestosis after short exposures. Although it is theoretically possible that lower 

level environmental exposures could contribute to disease over extended exposures, the 

data from this pilot study are too limited to support that finding.
39

b. Lung Cancer and Mesothelioma

Asbestos exposure is known to increase lung cancer incidence, particularly for high-level 

occupational exposures over an extended period of time (e.g., decades) (10,48,52). 

Additionally, some studies have indicated increased lung cancer and mesothelioma due to

high naturally occurring levels of asbestos or low dose environmental exposures (57–60). 

Longer asbestos fibers can penetrate into the deeper portions of the lung. Because asbestos 

is relatively insoluble, longer fibers cannot be physically removed by the body’s immune 

systems and may remain in the lung and cause damage. Although the exact mechanism for 

lung cancer is not known, it is believed the localized immune response to the asbestos may 

contribute to cancer. Fibers may also migrate out of the lung and cause mesothelioma, a 

cancer specific to the lining around the lungs. In general, shorter fibers (less than 5 

microns) are more efficiently cleared from the lung and therefore are less potent (10). 

Additionally, there is some indication that chrysotile asbestos is less potent than other 

forms of asbestos due to better clearance from the lungs.

EPA has established a cancer slope factor for asbestos to estimate risk in the general 

population due to chronic environmental exposures to asbestos (48).∗Factors that influence 

excess cancer estimates are age at time of exposure, sex, and cigarette smoking (52).†

EPA’s Integrated Risk Information System (IRIS) is used to develop risk estimates for 

comparison, with the understanding that smokers will be at higher risk. 

Air samples from several indoor areas with asbestos fibers detected in the settled surface 

dust did contain fibers as described by PCM analysis (0.001 f/cc to 0.003 f/cc).‡Because 

 

∗ This slope factor is based on epidemiologic studies and assumes a linear dose response for cancer, even at very low 

environmental doses (0.23 excess cancers per million people exposed for each f/cc of asbestos.) This type of cancer 

risk estimate may over predict risk and does not take into account any lower threshold for effect, which may exist. 

Additionally, the EPA slope factor was designed to apply equally to all types of asbestos, and all fibers greater than 5 

microns in length (IRIS).

† Variability in these factors is not accounted for in the EPA slope factor because it does not include synergistic effects 

with the effects of smoking (48).

‡ However, because asbestos as a percentage of settled surface dust was elevated, an area with significant dust may be 

capable of generating higher airborne levels of asbestos, especially during high activity.

Short-term exposures to asbestos, even for a continuous year of 

exposure at the highest estimated air concentration, are not expected to 

result in any adverse health effects.

Assuming worst-case theoretical assumptions, the highest fiber levels 

measured cannot rule out adverse health effects from chronic exposures 

(i.e., 30 years), but it is unlikely levels will remain elevated for that long. 

For individuals who conduct frequent cleaning of their residences, as 

recommended in this report, or participate in the U.S. Environmental 

Protection Agency cleaning/sampling program, it is unlikely that their 

exposure would resemble these worst-case conditions.
40

none of these air samples were analyzed by TEM, it is not known if they were asbestos 

fibers. For this analysis of a worst-case exposure, it will be assumed they are asbestos. 

Four of these samples were taken in common areas during normal daily activity. All other 

air samples, including the highest, 0.003 f/cc, were taken in residences that were 

aggressively sampled. Using the IRIS slope factor, no appreciable increase in cancer risk 

is seen when considering a 1-year continuous exposure at the highest fiber level cited 

(1×10-5 excess cancer risk).

If the highest measured PCM levels are assumed to be all asbestos fibers (a worst-case 

assumption) and were representative of long-term conditions (another worst-case 

assumption), the cumulative exposure for a continuous 30-year residence would result in a 

greater risk estimate for lung cancer and mesothelioma. Therefore these data cannot rule 

out the potential for long-term risk. However, the highest airborne level measured during 

this study is not necessarily representative of long-term exposure nor is the highest level 

necessarily all asbestos fibers. As presented in the discussion section of this report, it is 

expected that the ongoing cleaning of lower Manhattan should reduce levels of these 

materials over time, thus reducing long-term risk. Therefore cleaning should be continued 

and levels of asbestos monitored, until the data demonstrate long-term risk of lung cancer 

and mesothelioma are minimal.

8. Multiple Material Exposures

Each of the materials discussed previously may exist singly or in combination with other 

materials found in lower Manhattan. The combinations of materials found in this 

investigation are described in the discussion of results. When exposures to multiple 

materials occur together, there is some potential that the agents may interact with respect to 

their adverse effects. Agents may be additive if they impact an organ system similarly. 

Synergistic and antagonistic effects may also be seen if the agents either potentiate or 

disrupt the effects of other agents.

a. Irritant Effects

The effects of the alkaline minerals are most likely additive, although it should be noted 

that not all of the materials are equally caustic. Therefore, cumulative effects on pH would 

be the best measure of irritant effects based on the caustic nature of the dust. There may 

also be potentially additive or synergistic effects with the irritant effects of the SVF. The 

ability of either caustic action or the mechanical action of the fibers or minerals to degrade 

the protective properties of skin and mucus membranes may make tissue more susceptible 

to irritant effects. Additionally, because both types of actions may trigger localized immune 

responses, these irritants may potentiate each other.

b. Noncancer Pulmonary Effects

Several of the minerals detected contribute to fibrotic lung damage and may result in 

several diseases that reduce lung function including silicosis, asbestosis, other mineral 

fibroses, emphysema, and other respiratory disorders. The mechanisms and pathology of 
41

these conditions are similar, and the effects of these agents may be considered at least 

additive. However, each material has a different toxicity based on the mineral properties 

of that material. Less biopersistent materials, such as SVF, have the least long-term 

toxicity, and more biopersistent material, such as asbestos, have greater long-term toxicity. 

In general, the order of toxicity may be SVF < mica < silica < asbestos, based on solubility 

and availability for clearance. No factors currently exist to combine risk estimates for 

these different materials.

CONCLUSIONS

On the basis of the analytical results of samples taken between November 4 through 

December 11, 2001, and information collected during the sampling effort, the New York 

City Department of Health and Mental Hygiene and the U.S. Agency for Toxic Substances 

and Disease Registry make the following conclusions (not in order of importance).

• Total fiber counts of air samples taken in lower Manhattan were similar to the 

comparison areas above 59th Street sampled during this investigation. The six 

lower Manhattan areas that had elevated total fiber counts were re-examined by 

transmission electron microscopy (TEM) and scanning electron microscopy 

(SEM). The TEM and SEM results indicated that neither asbestos nor SVF 

contributed to the elevated fiber counts.

• Low levels of asbestos were found in some settled surface dust, primarily below 

Chambers Street. Many of the lower Manhattan locations sampled had been 

previously cleaned prior to this investigation. No asbestos was detected in the 

comparison indoor dust samples taken north of 59thStreet. The City of New York 

has conducted follow-up activities at the locations where asbestos was detected in 

settled surface dust. Only two follow-up locations, outdoor areas, required 

professional asbestos abatement. Following-up activity at the other locations did 

not find any asbestos containing materials.

• When compared with the results obtained from the comparison sampling 

locations, the lower Manhattan residential areas sampled by this investigation 

tended to have a greater percentage of SVF (primarily fiberglass), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum, mica, and halite) in settled surface dust. However, 

the frequency of detections and prevalence patterns of these minerals are similar in 

both residential areas.

• Exposure to significant amounts of synthetic vitreous fibers (SVF), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum) may cause skin rashes, eye irritation, and upper 

respiratory irritation, all of which have been voiced as concerns by citizens and 

first responders. If the reported irritant effects are associated with World Trade 

Center related materials, these effects will subside once exposure to SVF, mineral 

components of concrete, and mineral components of building wallboard end. Some 
42

people with pre-existing heart or lung disease (e.g., asthma) or a previous history 

of very high levels of exposures (occupational) to SVF, mineral components of 

concrete, and mineral components may be more sensitive to the irritant effects of 

SVF, mineral components of concrete, and mineral components of building 

wallboard.

• Sometimes mineral components of concrete (calcite and portlandite) and mineral 

components of building wallboard (gypsum, mica, and halite) were detected in air 

samples at higher estimated levels in lower Manhattan residential areas than in 

samples taken at comparison residential areas above 59th Street. These detected 

mineral levels are orders of magnitude below occupational standards. Although the 

occupational standards do not account for sensitive individuals or extended periods 

of exposure, they provide a comparison to an established health guidance value. 

The levels of minerals seen in airborne dust do not pose potential health hazards 

even for a continuous year of exposure at the highest levels detected.

• Some settled surface dust could become airborne if disturbed. Therefore, people 

could potentially inhale the asbestos, SVF, mineral components of concrete (quartz, 

calcite, and portlandite), and mineral components of building wallboard (gypsum, 

mica, and halite) found in settled surface dust of some lower Manhattan residences. 

Because we did not determine the weight of dust present in the areas sampled, it is 

not possible to determine whether any particular residence had an elevated dust 

loading. Appropriate continued frequent cleaning should minimize exposures.

• Several worst-case assumptions were made in order to assess the potential longterm public health risks of airborne asbestos and quartz. Some of the assumptions 

were that no cleaning of indoor spaces has occurred or will occur, all fibers found 

in air were asbestos fibers, and the highest levels detected last fall in air represent 

long-term air levels. Using these worst-case assumptions, prolonged exposure 

(decades) to airborne asbestos and quartz may increase the long-term, theoretical 

risk of people developing lung cancer and other adverse lung health effects (more 

than 1 additional case in 10,000 people exposed). For individuals who conduct 

frequent cleaning of their residences, as recommended in this report, or participate 

in the U.S. Environmental Protection Agency cleaning/sampling program, it is 

unlikely that their exposure would resemble these worst-case conditions. 

• A review of the building sampling results from this investigation indicates that 

there is not a consistent spatial distribution pattern of asbestos, SVF, mineral 

components of concrete, and mineral components of wallboard in air and settled 

surface dust. This indicates that the materials are heterogeneously distributed. 

There are many factors that may contribute to the heterogeneous distribution, 

including whether the area was cleaned (indoors and outdoors), cleaning method, 

date since last cleaning, and how much dust was initially in the area. It is not clear 

which factors contributed to this trend.
43

• 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 may or may not reflect 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).

RECOMMENDATIONS

On the basis of the conclusions of this investigation, the New York City Department of 

Health and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease

Registry make the following recommendations.

• Because more asbestos, synthetic vitreous fibers (e.g., fiberglass), mineral 

components of concrete (quartz, calcite, and portlandite), and mineral components 

of building wallboard (gypsum, mica, and halite) were found in settled surface dust 

in lower Manhattan residential areas when compared to comparison residential 

areas above 59th Street, the New York City Department of Health and Mental 

Hygiene and the U.S. Agency for Toxic Substances and Disease Registry are 

recommending that people continue to conduct frequent cleaning with HEPA 

vacuums and damp cloths/mops to reduce the potential for exposure.

• To ensure that the recommended frequent cleaning is effective and to ensure that 

the health of people of New York City is protected, the New York City Department 

of Health and Mental Hygiene and the U.S. Agency for Toxic Substances and 

Disease Registry are recommending additional monitoring of residential areas in 

lower Manhattan. In addition, an investigation should be conducted to better define 

background levels specific to the city of New York for asbestos, synthetic vitreous 

fibers, mineral components of concrete (quartz, calcite, and portlandite), and 

mineral components of building wallboard (gypsum, mica, and halite).

• Lower Manhattan residents concerned about possible World Trade Centerrelated dust in their residential areas can request cleaning and/or testing from the 

U.S. Environmental Protection Agency (EPA) by logging on to the agency's World 

Trade Center Web page at www.epa.gov/wtc or by calling the EPA hotline at 1-

877-796-5471.
44

PUBLIC HEALTH ACTION PLAN

The Public Health Action Plan (PHAP) for the World Trade Center response contains a 

description of actions to be taken by the New York City Department of Health and Mental 

Hygiene (NYC DOHMH), the U.S. Agency for Toxic Substances and Disease Registry 

(ATSDR), and/or other government agencies. The purpose of the PHAP is to ensure that 

this investigation not only identifies potential public health hazards, but also provides a 

plan of action designed to mitigate and prevent possible adverse human health effects 

resulting from exposure to hazardous substances in the environment.

A. Public Health Actions Taken

Shortly after the collapse of the World Trade Center towers, NYC DOHMH staff, along 

with other governmental and private organizations, provided respirators and fit checking 

for people participating in the recovery operations.

Beginning September 13, 2001, NYC DOHMH staff coordinated daily conference calls 

with the various governmental and private organizations that were conducting 

environmental sampling at and around the World Trade Center. These coordination calls 

ended in January 2002.

On September 15, 2001, the U.S. Department of Health and Human Services, the U.S. 

Environmental Protection Agency, and the U.S. Department of Labor formed the World 

Trade Center Environmental Assessment Working Group. The purpose of the group is to 

coordinate public health and occupational sampling and data review among the three 

federal agencies in support of the New York City Department of Health and Mental 

Hygiene and the New York State Department of Health. Other governmental (e.g., New 

York State Department of Health, New York State Department of Environmental 

Conservation, New York City Department of Health and Mental Hygiene, and the New 

York City Department of Environmental Protection) and private organizations (unions, 

research institutions, companies) participated on the Working Group.

Shortly after September 11, 2001, and through June of 2002, the U.S. Environmental 

Protection Agency (EPA), the Occupational Safety and Health Administration, the New 

York State Department of Environmental Conservation, the New York State Department of 

Health, and the New York City Department of Environmental Protection conducted 

frequent ambient environmental and occupational monitoring of many different types 

specifically for the World Trade Center response.

From September 18 through October 4, 2001, the National Institute for Occupational Safety 

and Health, Centers for Disease Control and Prevention, conducted occupational sampling 

and evaluation of the conditions at the World Trade Center.

From November 4 through December 11, 2001, NYC DOHMH and ATSDR, with 

assistance from the U.S. Public Health Service Commissioned Corps, conducted limited 

sampling of residential areas in lower Manhattan.
45

On February 4, 2002, NYC DOHMH and ATSDR provided the public with the preliminary 

findings (asbestos air and dust and synthetic vitreous fibers dust sampling results) of the 

limited residential sampling investigation conducted in November and December of 2001. 

Various public meetings were conducted to provide the public with the most relevant 

information.

On February 13, 2002, EPA formed the Indoor Air Task Force to help address the 

remaining indoor air quality issues in lower Manhattan.

On March 8, 2002, New York City created the lower Manhattan Air Quality Task Force.

On May 8, 2002, EPA and its federal, state, and city partners announced a comprehensive 

plan to ensure that residences impacted by the collapse of the World Trade Center have 

been properly cleaned.

On June 1, 2002, lower Manhattan residents concerned about possible World Trade 

Center-related dust in their residential areas could begin to request cleaning and/or testing 

from EPA by logging on to the agency's World Trade Center Web page at 

www.epa.gov/wtc or by calling the EPA hotline at 1-877-796-5471.

B. Public Health Actions Planned

During the summer of 2002, EPA and its federal, state, and city partners will conduct 

additional sampling of settled surface dust and air of residential areas not impacted by the 

collapse of the World Trade Center towers. The purpose of this investigation is to better 

define the New York City-specific background levels of asbestos, synthetic vitreous fibers, 

and quartz. Mineral components of concrete (calcite and portlandite) and mineral 

components of building wallboard (gypsum, mica, and halite) will also be investigated.

During the summer of 2002, EPA and its federal, state, and city partners will conduct an 

investigation to determine the effectiveness of various cleaning methods to remove World 

Trade Center-related material.

In late summer/early fall 2002, EPA will begin to conduct cleaning and/or testing of 

residential areas requested by lower Manhattan residents.

The New York City Department of Health and Mental Hygiene and the U.S. Agency for 

Toxic Substances and Disease Registry will establish a unified World Trade Center 

Exposure Registry of people who may have been exposed to harmful substances resulting 

from the collapse of the World Trade Center towers.

The New York City Department of Health and Mental Hygiene and the U.S. Agency for 

Toxic Substances and Disease Registry will continue to work with other federal, state, and 

local agencies to provide information on the sampling results to the citizens of New York 

and to help interpret the possible health effects of contaminants found.
46

REFERENCES

1. Matthews, Kevin. A World Trade Center@ 

Http://www.GreatBuildings.com/buildings/World_Trade_Center.html

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51

AUTHORS AND ACKNOWLEDGMENTS

New York City Department of Health and Mental Hygiene

Jessica Leighton, PhD

Nancy Loder Jeffery, RN, MPH

Christopher D’Andrea, MS

Kenneth Carlino, MS

Jim Miller, MD

CAPT Thomas Matte, MD, MPH

Vincent Coluccio, Dr.PH

Agency for Toxic Substances and Disease Registry

DHAC World Trade Center Response Team:

RADM Robert C. Williams, PE, DEE

CAPT Sven Rodenbeck, ScD, PE, DEE

CAPT Virginia Lee, MD, MPH, MA

Lynn Wilder, MS, CIH

CDR Danielle DeVoney, PhD, PE

LCDR Sue Neurath, PhD

Loretta Bush

Technical Support Team:

Janet L. Heitgerd, PhD

Louisa M. Rosenberg, MA

B. Kathy Skipper, MA, APR

Pam S. Uveges

Technical Consultation Team:

John Wheeler, PhD

Susan Moore, MS

Karl Markewitz, PhD

CDR Peter Kowalski, MPH, CIH, CSP

LCDR Clement J. Welsh, PhD, MPH

David Mellard, PhD

Debra Gable, MS

Greg Zarus, MS

On-Site Technical Team:

CAPT Robert Johnson, MD

LCDR Tim Walker, MPH, RS, CIH

CAPT Ralph C. O’Connor, Jr., PhD

CDR Stephen Blackwell, RS, MPH

CDR Joe Maloney, REHS, MPH

CDR Richard Sullivan, REHS

CDR Mark D. Miller, RS, MPH
52

LCDR Ketna Mistry, MD

Barbara M. Cooper, MSPH

John R. Crellin, PhD

LCDR Clement J. Welsh, PhD, MPH

Christine Roshheim, DDS, MPH

Diane M. Drew, RN, MPA

Dona L. Orti, MS, MPH

LT Steve Dearwent, MPH

CDR Steven Inserra, MPH, RS

David R. Fowler, PhD

Azania A. Heyward-James, MEd

LCDR Robert B. Knowles, MS, REHS

Annmarie DePasquale, MPH

Dianyi Yu, MD

LT Tarah Somers

Grant Baldwin, MPH, CHES

Debra Gable, MS

U.S. Public Health Service Commissioned Corps Readiness Force (Sampling Teams)

CAPT Cliff Moseley, MS, CIH

CDR Richard E. Turner, REHS, MPH

LCDR Alan Parham, MPH, REHS

CDR Leo Blade, CIH

LCDR Richard A. Orlando, MSEH

CDR Daniel Almagure, MS, RS

LCDR Jeffery A. Church, REHS, MPH

CDR Tim Radtke, CIH

LT Hayden R. Hardie, CIH

LCDR Robert B. Knowles, MS, REHS

LCDR Nathan C. Tatum, PE

New York State Department of Health

Robert Chinery

Randi J. Walker
53

World Trade Center Environmental Assessment Working Group

Formed on September 15, 2001, the World Trade Center Environmental 

Assessment Working Group is made up of representatives from the U.S. 

Department of Health and Human Services, the U.S. Environmental Protection 

Agency, and the U.S. Department of Labor. Other governmental (e.g., New York 

State Department of Health, New York State Department of Environmental 

Conservation, New York City Department of Health and Mental Hygiene and New 

York City Department of Environmental Protection) and private organizations 

(unions, research institutions, companies) participated on the Working Group. The 

purpose of the group is to coordinate public health and occupational sampling and 

data review among the three federal agencies in support of the New York City 

Department of Health and Mental Hygiene and the New York State Department of 

Health.
54

TABLES
55

Table 1

General Information on the World Trade Center Towers

Height Tower One: 1,368 feet Tower Two: 1,362 feet

Weight 1.5 million tons

Statistics 110 floors

6 basements (with 2 subway stations and PATH train station)

1 underground mall

43,600 windows

97 passenger elevators and 6 freight elevators

300 computer mainframes

Air conditioning had 60,000 tons of cooling capacity

Rentable Space 43,200 square feet per floor 10,000,000 total square feet

Owners and Operators Port Authority of New York and New Jersey

Groundbreaking August 5, 1966

Opening Ceremony April 4, 1973 (Parts were opened between 1970–1973)

Steel: 200,000 tons

Concrete: 425,000 cubic yards

Glass: 600,000 square feet

Construction Materials

Electric cables: 12,000 miles

Table 2

2000 Census Block Level Population

Distance From WTC Total Population Housing Units

One-Quarter Mile 6,965 4,617

One-Half Mile 17,596 10,768

Three-Quarter Mile 29,667 16,482

The 16-acre site of the World Trade Center was buffered, and an aerial proportion technique 

was used to estimate the number of persons living in the area.
56

Table 3

Number of Buildings and Areas Within Buildings Sampled for Settled Surface Dust:

Analyzed for Asbestos by PLMa and TEMb, SVFc by PLM, and Minerals by XRDd

Due to available sample size and analytical objectives, some samples were not analyzed by each method.

Lower Manhattan Above 59th Street

Buildings 29 4

Residential Units 57 5

Common Areas 26 3

Outdoors 14 0

Table 4

Number of Buildings and Areas Within Buildings Sampled for Fibers in Air:

Analyzed for Total Fibers by PCMe, Asbestos by TEM, and SVF by SEMf

Lower Manhattan Above 59th Street

Total Fibers 

(PCM)

Asbestos 

(TEM)

SVF (SEM) Total Fibers 

(PCM)

Asbestos 

(TEM)

SVF (SEM)

Buildings 30 5 4 4 0 4

Residential Units 59 3 3 5 0 5

Common Areas 29 3 2 3 0 1

Outdoors 29 0 0 3 0 3

Table 5

Number of Locations Sampled for Minerals in Airborne Dust,

Analyzed by XRD for Minerals

Lower Manhattan Above 59th Street

PM100 PM10 PM4 PM2.5 PM100 PM10 PM4 PM2.5

Buildings 26 28 30 10 3 4 4 3

Residential 

Units 47 52 57 18 3 5 5 2

Common 

Areas 26 27 29 8 2 2 3 2

Outdoors 26 26 29 8 2 3 3 2

Notes:

a. PLM = polarized light microscopy

b. TEM = transmission electron microscopy

c. SVF = synthetic vitreous fibers

d. XRD = x-ray diffraction

e. PCM = phase contrast microscopy

f. SEM = scanning electron microscopy

Settled surface dust and air samples could not always be obtained together from the same sampling location.
57

Table 6

Summary of Locations With Asbestos or Synthetic Vitreous Fibers (SVF) in Settled Surface Dust

Sampling locations that had either asbestos in the dust by PLM or TEM analysis or SVF in the settled surface dust by 

PLM analysis. Ranges of asbestos and SVF values for each type of location are included.

Sampling 

Locations:

Lower 

Manhattan

Total Number of 

Locations Sampleda

Number of 

Locations with 

Asbestos in 

Settled Surface 

Dust

(% of locations 

detected)b

Range of

Asbestos Foundc

Number of 

Locations with 

SVF in Settled 

Surface Dust 

(% of 

locations 

detected)d

Range of

SVF Founde

Outdoor

Asbestos (PLM) = 14

Asbestos (TEM) = 12

SVF (PLM) = 14

6

(43%)

<1%–3.4 % 11

(79%)

1%–72%

Common

Asbestos (PLM) = 26

Asbestos (TEM) = 25

SVF (PLM) = 26

5

(19%)

<1%–1.5% 14

(54%)

5%–27%

Residential

Asbestos (PLM) = 57

Asbestos (TEM) = 52

SVF (PLM) = 57

10

(18%)

<1%–1.5% 26

(46%)

2%–35% f

Whole 

Building

Asbestos (PLM) = 29

Asbestos (TEM) = 29

SVF (PLM) = 29

12

(41%)

<1%–3.4% 21

(72%)

2%–72%

Sampling 

Locations: 

Comparison 

Buildings

Total Number of 

Locations Sampleda

Number of 

Locations With 

Asbestos in 

Settled Surface 

Dust

(% of locations 

detected)b

Range of

Asbestos Foundc

Number of 

Locations 

With SVF in 

Settled 

Surface Dust 

(% of 

locations 

detected)d

Range of

SVF Found e

Common

Asbestos (PLM) = 3

Asbestos (TEM) = 3

SVF (PLM) = 3

0

(0%)

None Detected 

by PLM or TEM

0

(0%)

None Detected 

by PLM

Residential

Asbestos (PLM) = 5

Asbestos (TEM) = 4

SVF (PLM) = 5

0

(0%)

None Detected 

by PLM or TEM

0

(0%)

None Detected 

by PLM

Notes:

a. All dust samples were initially analyzed by polarized light microscopy (PLM). Transmission electron microscopy (TEM) 

analysis was performed to confirm the absence of asbestos if not detected by PLM analysis.

b. The number of locations containing asbestos in dust reflects locations with asbestos detected by either PLM or TEM 

(reported as <1% or more). The percentage of locations with asbestos detected is calculated from the total number of dust 

samples.

c. The range represents the highest value detected at a location (PLM or TEM).

d. The percentage of locations with synthetic vitreous fibers (SVF) detected is calculated from the number of SVF PLM 

samples.

e. Some locations had an additional co-located sample obtained, the range shown considers the highest measured value for 

each sampling location.

f. One residential unit had an extra settled surface dust sample (taken from a window sill), which contained 40% SVF by PLM.
58

Table 7

Summary of Mineral Components of Settled Surface Dust by Sampling Location

Outdoor Settled Surface Dust of Lower Manhattan

Number of 

Occurrences,

14 samples 

totala

Minimum 

Detected

(% by weight)

Maximum 

Detected

(% by weight)

Average of 

Detections

(% by weight)

Number 

Above 

Comparisonb

Quartz 14 (100%) 1 Jd27 J 12 J NAc

Calcite 13 (93%) 0.8 J 19 J 6 J NA

Portlandite 12 (86%) 0.07 J 6 J 2 J NA

Gypsum 11 (79%) 0.03 J 27 J 6 J NA

Mica 9 (64%) 0.05 J 0.3 J 0.1 J NA

Halite 7 (50%) <0.03 J 0.1 J 0.05 J NA

Outdoor samples were not taken from comparison areas above 

59th Street because no settled surface dust was visible.

Common Area Settled Surface Dust of Lower Manhattan Common Areas of Comparison Areas Above 59th Street

Number of 

Occurrences,

26 samples 

total a

Minimum 

Detected

(% by weight)

Maximum 

Detected

(% by weight)

Average of 

Detections

(% by weight)

Number 

Above 

Comparisonb

Number of 

Occurrences,

3 samples total

a

Minimum 

Detected

(% by weight)

Maximum 

Detected

(% by weight)

Average of 

Detected Values

(% by weight)

Quartz 21 (81%) 0.03 J 25 J 5 J 6 (23%) 2 (67%) 1 J 1 J NA

Calcite 15 (58%) 0.02 J 10 J 3 J 9 (35%) 2 (67%) 0.03 J 0.4 J NA

Portlandite 13 (50%) 0.04 J 4 J 2 J 9 (35%) 1 (33%) 0.05 J 0.05 J NA

Gypsum 23 (88%) 0.07 J 20 J 5 J 6 (23%) 2 (67%) 2 J 3 J NA

Mica 5 (19%) 0.06 J 0.6 J 0.2 J 5 (19%) 0 (0%) ND ND NA

Halite 4 (15%) 0.04 J 0.06 J 0.05 J 1 (4%) 1 (33%) 0.04 J 0.04 J NA

Residential Units Settled Surface Dust of Lower Manhattan Residential Units of Comparison Areas Above 59th Street

Number of 

Occurrences,

57 samples 

totala

Minimum 

Detected

(% by weight)

Maximum 

Detected

(% by weight)

Average of 

Detections

(% by weight)

Number 

Above 

Comparisonb

Number of 

Occurrences,

5 samples 

total a

Minimum 

Detected

(% by weight)

Maximum 

Detected

(% by weight)

Average of 

Detected Values

(% by weight)

Quartz 30 (53%) 0.05 J 31 J 9 J 15 (26%) 2 (40%) 1 J 2 J NA

Calcite 20 (35%) 0.02 J 21 J 8 J 13 (23%) 1 (20%) 0.9 J 0.9 J NA

Portlandite 21 (37%) 0.05 J 8 J 2 J 17 (30%) 2 (40%) 0.08 J 0.08 J NA

Gypsum 45 (79%) 0.05 J 30 J 4 J 9 (16%) 4 (80%) 2 J 4 J 3 J

Mica 5 (9%) 0.03 J 0.3 J 0.1 J 1 (2%) 1 (20%) 0.08 J 0.08 J NA

Halite 6 (11%) 0.03 J 0.1 J 0.06 J 0 (0%) 1 (20%) 0.4 J 0.4 J NA

a. Shows the number of samples where the mineral was detected and the percentage based on the number of samples obtained from this area.

b. Shows the number of results, and the percentage of samples obtained from this area, that had estimated values greater than the maximum levels found at locations above 59th Street.

c. NA = not applicable.

d. J = estimated.
59

Table 8

Summary of Results for Locations With Airborne Fiber Levels 

Higher Than Levels in Comparison Areas Above 59th Street.

Air samples were collected and analyzed by phase contrast microscopy for total fibers

(NIOSH 7400). All samples with fiber counts higher than the comparison areas above 59th Street were

re-analyzed to determine if those fibers were asbestos, synthetic vitreous fibers (SVF), or other material.

Building

(Area)

Aggressive 

Samplinga

Fibers in Air by 

PCM 

(f/cc)b

Asbestos in 

Dust by PLM 

or TEMc

Asbestos in Air 

by TEM 

(f/cc)b

SVF in Dust 

by PLM

SVF in Air by 

SEM 

(f/cc)b

1

(Residence) No 0.006 NDg

<0.001d20% 0.000162

2

(Common) No 0.005 NDg<0.001d27% 0.000255

19

(Common) No Overloadede NDg<0.006f ND Not analyzed

24

(Residence) No 0.005 NDg<0.001d10% 0.000037

26

(Common) No 0.004 NDg<0.001d5% <0.00004

26

(Residence) No 0.012 NDg<0.001d ND <0.00004

a. Aggressive sampling refers to a technique used in some residential units where the vacuum exhaust (used for 

settled dust sample collection) was used to stir up the settled surface dust before the air sampling began.

b. f/cc = fibers in each cubic centimeter (cc) of air as determined using phase contrast microscopy (PCM), 

transmission electron microscopy (TEM), or scanning electron microscopy (SEM) methods. This is calculated 

from the number of fibers seen on the air filter and the volume of air pulled through the filter measured in cubic 

centimeters of air.

c. Value shown represents the highest of polarized light microscopy (PLM) or TEM results for this area.

d. The TEM method employed here, National Institute of Occupational Safety and Health (NIOSH) 7402, counts 

fibers of the same size as those detected by PCM analysis. Fibers reported here are greater than or equal to 5 

microns in length and 0.25 microns in width.

e. A building renovation project was occurring near the area of this sampling equipment. Construction dust and 

building insulation material may have influenced this sample.

f. Sample processing of the overloaded filter involved transferring the material to a new filter; this process provides 

less analytical sensitivity, resulting in a higher detection limit.

g. ND = not detected.
60

Table 9

Summary of Airborne Fibers at Locations Where Asbestos Was Detected in Settled Surface Dust

Outdoor Areas in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

1 Outdoor <1% 22% No 0.001 f/cc

2

e Outdoor 1.3% 28% No 0.003 f/cc

5 Outdoor 3.4% 25% No 0.002 f/cc

7 Outdoor 1.7% 35% No <0.001 f/cc

15 Outdoor 1.9% 72% No <0.001 f/cc

27 Outdoor <1% 15% No <0.001 f/cc

Common Areas in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

4 Common <1% 15% No 0.001 f/cc

6 Common <1% 10% No <0.001 f/cc

10 Common 1.5% 20% No 0.002 f/cc

24 Common <1% 5% No 0.001 f/cc

27 Common <1% 10% No <0.001 f/cc

Residential Units in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

4 Residence 1 <1% 2% Yes <0.001 f/cc

4 Residence 2 <1% 5% Yes 0.001 f/cc

5 Residence 1 <1% 10% Yes 0.002 f/cc

5 Residence 2 <1% 20% Yes <0.001 f/cc

9 Residence 1 <1% 2% Yes 0.001 f/cc

9 Residence 2 <1% 5% Yes 0.003 f/cc

11 Residence 1 <1% ND Yes <0.001 f/cc

11 Residence 2 1.5% ND Yes <0.001 f/cc

15 Residence 1 <1% ND Yes <0.001 f/cc

27 Residence 1 <1% 10% No <0.001 f/cc

a. Value shown is highest of the reported polarized light microscopy (PLM) and transmission electron microscopy (TEM) 

results for this area.

b. SVF = synthetic vitreous fibers. Measured by PLM analysis.

c. Aggressive sampling refers to a technique used in some residential units where the vacuum exhaust (used for settled dust 

sample collection) was used to stir up the settled surface dust before the air sampling began.

d. f/cc = the fibers in each cubic centimeter (cc) of air. This is calculated from the number of fibers seen on the air filter and the 

volume of air pulled through the filter measured in cubic centimeters.

e. Building 2 also had a co-located dust sample; values represent the highest measured result.
61

Table 10

Summary of Airborne Fibers at Locations Where Only Synthetic Vitreous Fibers (SVF) Were Detected in 

Settled Surface Dust

Outdoor Areas in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

18 Outdoor NDf30% No <0.001 f/cc

24 Outdoor NDf55% No 0.002 f/cc

28 Outdoor NDf15% No <0.001 f/cc

Common Areas in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

2 Common NDf27% No 0.005 f/cce

7 Common NDf5% No 0.001 f/cc

14 Common NDf5% No 0.003 f/cc

25 Common NDf5% No <0.001 f/cc

26 Common NDf5% No 0.004 f/cce

28 Common NDf10% No 0.001 f/cc

Residential Units in Lower Manhattan

Building Area Asbestos in Dust

(PLM or TEM)a

SVF in Dust (PLM)b Aggressive 

Samplingc

Fibers in Air 

(PCM)d

1 Residence 1 NDf20% No 0.006 f/cce

1 Residence 2 NDf20% Yes <0.001 f/cc

2 Residence 1 NDf25% No <0.001 f/cc

2 Residence 2 NDf20% Yes 0.002 f/cc

6 Residence 1 NDf15% Yes <0.001 f/cc

6 Residence 2 NDf15% Yes <0.001 f/cc

7 Residence 2 NDf5% No <0.001 f/cc

10 Residence 1 NDf15% Yes 0.001 f/cc

10 Residence 2 NDf10% Yes 0.001 f/cc

12 Residence 1 NDf5% No 0.001 f/cc

12 Residence 2 NDf5% Yes <0.001 f/cc

13 Residence 1 NDf10% Yes 0.003 f/cc

15 Residence 2 NDf5% Yes <0.001 f/cc

18 Residence 1 NDf30% No 0.002 f/cc

18 Residence 2 NDf35% No 0.002 f/cc

24 Residence 2 NDf10% No 0.005 f/cce

25 Residence 1 NDf5% No <0.001 f/cc

27 Residence 2 NDf10% No <0.001 f/cc

a. Value shown is highest of the reported polarized light microscopy (PLM) and transmission electron microscopy (TEM) 

results for this area.

b. SVF = synthetic vitreous fibers. Measured by PLM analysis.

c. Aggressive sampling refers to a technique used in some residential units where the vacuum exhaust (used for settled dust 

sample collection) was used to stir up the settled surface dust before the air sampling began.

d. f/cc = the fibers in each cubic centimeter (cc) of air. This is calculated from the number of fibers seen on the air filter and the 

volume of air pulled through the filter measured in cubic centimeters.

e. Scanning electron microscopy (SEM) and TEM results for these air samples are available and shown on Table 8.

f. ND = not detected.
62

Table 11

Summary of Minerals in Indoor and Outdoor Air From Lower Manhattan and Comparison Buildings Above 59th Street a, b, c

Air Samples from Lower Manhattan Air Samples From Comparison Buildings

Number 

of 

Samples

Quartz Calcite Portlandite Gypsum Mica Halite

Number 

of 

Samples

Quartz Calcite Portlandite Gypsum Mica Halite

PM 100

Number 

(Frequency 

detected %)

Air Concentration 

(μg/m3)

101

14 (14%)d

3–13 Je

9 (9%)

3–14 J

8 (8%)

16–95 J

24 (24%)

3–14 J

2 (2%)

9–13 J

4 (4%)

4–14 J

7

NDf ND ND 1 (14%)

3 J

ND ND

PM 10

Number 

(Frequency 

detected %)

Air Concentration 

(μg/m3)

105

11 (10%)

3–12 Je

10 (10%)

3–5 J

10(10%)

14–25 J

33 (31%)

3–14 J

1 (1%)

8 J

5 (5%)

4–5 J

10

ND ND ND 3 (30%)

3 J

ND ND

PM 4

Number 

(Frequency 

detected %)

Air Concentration 

(μg/m3)

114

13 (11%)

4–19 J

13 (11%)

4–10 J

12 (11%)

21–84 J

40 (35%)

4–15 J

4 (4%)

14–43 J

3 (3%)

7–19 J

11 ND ND ND 3 (27%)

5 J

ND ND

PM 2.5

Number 

(Frequency 

detected %)

Air Concentration 

(μg/m3)

34

1 (3%)

3 J

ND ND 1 (3%)

3 J

ND ND

6

ND ND ND 1 (17%)

3 J

ND ND

Range of Detection Limits (μg/m3)

PM 100

PM 10

PM 4

PM 2.5

2–5 J

2–5 J

4–6 J

2–4 J

2–5 J

2–5 J

4–6 J

2–4 J

12–26 J

12–26 J

20–30 J

13–20 J

2–5 J

2–5 J

4–6 J

2–4 J

7–15 J

7–15 J

11–17 J

7–11 J

4–8 J

4–8 J

6–9 J

4–6 J

2–5 J

2–5 J

4–6 J

2–4 J

2–5 J

2–5 J

4–6 J

2–4 J

12–26 J

12–26 J

20–30 J

13–20 J

2–5 J

2–5 J

4–6 J

2–4 J

7–15 J

7–15 J

11–17 J

7–11 J

4–8 J

4–8 J

6–9 J

4–6 J

a. Where two samples were co-located—the greatest value of the two was included in this summary. Each location is only represented once in this table.

b. Concentrations shown are estimated values, indicated by “J.”

c. Air samples from all locations, indoor and outdoor, are pooled in this table due to uncertainties in the data.

d. Cristobalite, a different crystalline form of silica, was found in one Lower Manhattan air sample at 15 micrograms per cubic meter of air (μg/m3) J in the PM 100 fraction.

e. J = estimated.

f. ND = not detected.
63

Table 12

Highest Amount of Materials Measured in the Indoor Settled Dust of Each Building

Building Number Quartz

(%) a, d, e

Gypsum 

(%)a, d, e

Asbestos

 (%)b, f

SVF 

(%)c, f

Comparison 

Locations 31-34 2 J 4 J Non-Detect Non-Detect

1 31 J 30 J Non-Detect 20

2 23 J 14 J Non-Detect 27

3 Not Sampled Not Sampled Not Sampled Not Sampled

4 14 J 9 J <1 15

5 11 J 9 J <1 20

6 27 J 20 J <1 15

7 21 J 15 J Non-Detect 5

8 28 J 17 J Non-Detect Non-Detect

9 25 J 16 J <1 7

10 3 J 0.8J 1.5 20

11 2 J 2 J 1.5 Non-Detect

12 4 J 1 J Non-Detect 5

13 0.05 J 1 J Non-Detect 10

14 0.03 J 2 J Non-Detect 5

15 0.4 J 1 J <1 5

16 Non-Detect 0.9 J Non-Detect Non-Detect

17 2 J 2 J Non-Detect 2

18 0.9 J 1 J Non-Detect 35

19 1 J 2 J Non-Detect Non-Detect

20 0.9 J 1 J Non-Detect Non-Detect

21 0.9 J 2 J Non-Detect Non-Detect

22 14 J 2 J Non-Detect 3

23 2 J 1 J Non-Detect Non-Detect

24 0.03 J Non-Detect <1 10

25 Non-Detect 2 J Non-Detect 5

26 0.7 J 2 J Non-Detect 5

27 0.04 J 1 J <1 10

28 Non-Detect 1 J Non-Detect 10

29 1 J 2 J Non-Detect Non-Detect

30 1 J 4 J Non-Detect Non-Detect

a. Minerals were measured by XRD. Quartz is considered representative of the relative presence of portlandite 

and calcite (all are associated with concrete).

b. Asbestos value represents the highest of the PLM and TEM result for each location.

c. SVF is synthetic vitreous fiber and was measured by PLM.

d. Results shown are estimated values, indicated by “J.”

e. % = weight of mineral per weight of dust.

f. % = roughly area of fibers per area of dust.
64

FIGURES
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82

SAMPLING EVENT PHOTOGRAPHS
83

Photo 1. Residential Vacuum Sample

Photo 2. Residential Air Sampling 
84

Photo 3. Residential Air Sampling 

Photo 4. Residential Air Sampling 
85

Photo 5. Residential Air Sampling 

Photo 6. Residential Air Sampling 
86

Photo 7. Outside Bulk Sampling

Photo 8. Sampling Head
87

APPENDICES
88

Appendix A. Particulate Matter Quality Assurance/Quality Control Discussion
89

General Notes on Quality Assurance/Quality Control Procedures

Quality assurance/quality control (QA/QC) procedures are used to ensure the precision, accuracy, 

completeness, representativeness, comparability, and method detection limit of the results. The colocated samples and blanks are a primary means of assessing each of the data quality indicators. 

Comparing the results of two co-located samples provides information on the precision of the 

results as a whole. Comparing sample results to their associated blanks can help identify some 

potential errors in accuracy. Comparing the results received to those expected and necessary to 

draw conclusions about the data can help in understanding the completeness and reliability of the 

results. Comparability can be assessed by looking at the results taken from different sampling 

locations of the same building—or from different buildings for the same type of location. The 

reviews are generally qualitative and provide a qualitative assessment of how well the data 

actually represents the sampled location.

The method detection limit is a more quantitative review. It is accomplished by calculating the 

lowest result the analytical method can accurately identify. It is based on an analysis of the blank 

samples and is specific for the sampling/analysis method. Reliable information can only be 

obtained from sample results with method detection limits significantly lower than the average 

value of the results and significantly lower than any comparison values to which the sample results 

will be compared.

The analytical results of the concentration of airborne particulate matter were provided by the 

laboratory as the initial weight of the filter prior to the sampling event and the final weight of the 

filter after the sampling event. The concentration of the particulate matter was calculated by 

dividing the weight of the material collected on the filter by the volume of air drawn through the 

filter by the pump using the following formulas.

Weight Gain of Filter = Final Weight – Initial Weight

Sample Volume = Average Pump Flow Rate × Sample Collection Time

Average Air Sampling Pump Flow Rate=(Presampling Flow Rate + Postsampling Flow Rate) ÷ 2

Concentration = Weight Change ÷ Sample Volume

Airborne Particulate Matter Sample Results

Each area that was sampled for airborne asbestos was also sampled for airborne particulate matter 

(PM). The sample results from the PM measurements did not meet the data QA/QC objectives. A 

variety of statistical and graphical analyses were performed on, and with, the measured results in 

an attempt to identify the cause and extent of inconsistencies of the measured results. A subset of 

the measured results that are not potentially affected by these inconsistencies were not identified. 

Therefore, the entire data set describing airborne particulate matter concentrations was rejected. In 

addition, the specific cause of the inconsistencies was not identified. The following information 

explains why the airborne particulate matter results were rejected.
90

Ideally, the particulate matter data would have provided information about the airborne 

concentration with an aerodynamic diameter of 100 microns and less (PM100), of 10 microns and 

less (PM10), of 4 microns and less (PM4), and of 2.5 microns and less (PM2.5). These different 

size fractions (PM100, PM10, PM4, and PM2.5) are collected using slightly different equipment, 

but following the same basic procedures. A pump draws air into a sampling head, and size 

specific particulate matter is deposited onto a filter. The difference in filter weight, before and 

after the sampling, represents the mass of the particulate matter that was captured by the filter. 

Knowing the presampling and postsampling air flow rates of the pump and the time duration for 

sample collection allows us to calculate the average volume of air that was drawn through the 

filter. The concentration of the size fraction in the sampled air is then calculated by dividing the 

PM mass by the air volume sampled.

In addition to the filters that were used to measure the concentration of airborne particulate matter, 

the laboratory also sent filters to be used as field blanks. Two blanks were sent for each PM 

fraction for each of the two sampling teams for each building. The blanks traveled with the sample 

filters, went to the sampled building or area, and were treated just like the sample filters—except 

that they were not used. Ideally, there should be very little difference in the weight of the blanks 

before the sampling and after the sampling because they were not used. A weight gain in field 

blanks may indicate improper sample handling in the field or problems in filter weighing in the 

lab. For the latter a decrease in post field blank filter weight is also an indication of lab weighing 

error.

The graph shown with this discussion shows the frequency distribution of the air sample filter 

weight change in all but seven of the blanks used. Seven blanks were not included because their 

weight change (from a negative -90 milligrams (mg) to 5.99 mg) was greater than the limits shown 

in this graph (-0.2 mg to 0.5 mg). The vertical axis represents the number of blanks that had a 

weight change within 0.01 mg of the weight change shown on the horizontal axis.
91

Frequency Distribution of Weight Change in Selected Blanks

0

2

4

6

8

10

12

14

16

18

-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

Weight Change [mg]

Frequency

PM100

PM10

PM4

PM2.5

Lower LOD

Upper LOD

The dashed vertical lines show the upper and lower limits of detection expected for this method 

(+/– 0.03 mg). The distance between limits of detection represents the maximum weight gain 

expected for the blanks if the entire sampling procedure was followed as required by standard 

sampling methodologies. All of the size fractions had at least two blanks outside the limit of 

detection boundaries. (The two out of range blanks for PM100 are not shown on the graph because 

they are also beyond the boundaries of the graph). Approximately 6% of the PM100, 70% of the 

PM10, 57% of the PM4, and 8% of the PM2.5 blanks had weight changes greater than the limit of 

detection.

In general, blanks are used (1) to assess the ability of the sampling and laboratory analysis 

methodology to accurately estimate the concentration of particulate matter in the air at the sampled 

location and (2) to validate that there is no filter contamination problem from the time the blanks 

are initially weighed in the laboratory until the time the blanks are weighed in the laboratory after 

sampling. Errors could occur at any step in the process.

The large weight change of the blanks indicates errors in either the laboratory weighing process or 

the air sampling process. The graph illustrates that the results of the airborne particulate matter 

sampling cannot be used to reliably estimate the actual concentration of any of the particulate 

matter size fractions; therefore, the entire data set was rejected from further consideration.
92

Appendix B. Survey Result
93

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

1 Outside 28 None Visible

1 Common 0 SI N C None Visible Prepared for asbestos abatement

1 Residence 1 2 LI Y U None N Large Amount Large amount of WTC dust; more than other locations sampled

1 Residence 2 0 NI N U None Y None Visible

2 Outside 1 Y None Visible

2 Common 0 NI N C Slight Amount

2 Residence 1 0 SI N Y C N None Visible Residence window faces WTC site

2 Residence 2 0 SI N U C Y None Visible

3 Outside 0 N None Visible Sampled from courtyard several floors up

3 Common 0 LI N AA None Visible

3 Residence 1 0 LI N Y AA N None Visible

3 Residence 2 0 MI N Y C N None Visible

4 Outside 0 N Slight Amount

4 Common 0 NI Y O None Visible

4 Residence 1 0 SI Y N None Y None Visible

4 Residence 2 0 SI Y N None Y None Visible

5 Outside 50 Y Large Amount

5 Common 0 SI N AA None Visible

5 Residence 1 6 LI LI Y AA Y None Visible

5 Residence 2 6 LI LI Y AA Y None Visible Room looks clean but lots of WTC dust outside one window sill

6 Outside 200 N None Visible

6 Common 0 SI N C Couldn't identify photos for common area

6 Residence 1 0 LI N U C Y None Visible

6 Residence 2 0 SI N U C Y None Visible

7 Outside 2 N None Visible

7 Common 0 MI N C None Visible

7 Residence 1 0 MI N Y C N None Visible

Many window sills (not sure where) have significant amount of WTC 

dust on outside ledge, not noticeable on inside of window.

7 Residence 2 0 MI N Y C N None Visible Resident has window view of WTC site
94

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

8 Outside 0 N None Visible

8 Common 0 MI N C None Visible

8 Residence 1 1 SI N Y O N None Visible

8 Residence 2 1 MI N Y C N None Visible Resident has window view of WTC site

9 Outside 2 N

None Visible 

in Picture

9 Common 0 LI N C None Visible

Utility/road construction occurring near building and across the 

street from the front door.

9 Residence 1 0 MI Y Y C Y None Visible

9 Residence 2 0 MI Y Y C Y Slight Amount

10 Outside 0 Y Slight Amount

10 Common 0 SI N AA None Visible

10 Residence 1 0 NI N Y AA Y None Visible View of Statue of Liberty

10 Residence 2 1 SI N Y AA Y None Visible

11 Outside 0 LI N None Visible Looks like many dried, fallen leaves on sidewalk

11 Common 0 SI N MS None Visible

11 Residence 1 0 SI N V None Y None Visible

11 Residence 2 0 UNK N V UNK Y None Visible Wall AC unit was removed, it was just a hole to the outside

12 Outside 0 N None Visible Looks like many dried, fallen leaves on sidewalk

12 Common 0 SI N MS None Visible

12 Residence 1 0 MI Y V None N Large Amount

Very messy, doesn't look like “WTC dust” (has “'post-move-out”' 

look)

12 Residence 2 0 SI N V None Y None Visible

13 Outside 0 N Slight Amount A little messy, but does not look like WTC dust

13 Common 0 MI N MS None Visible

13 Residence 1 0 MI N V C Y None Visible

13 Residence 2 0 MI Y V C Y Large Amount Very messy, but not with WTC dust (post-move-out look)

14 Outside 0 N None Visible

14 Common 0 SI N C None Visible

Air sample from garden area; no bulk sample taken; WTC dust 

visible on neighboring building.

14 Residence 1 0 MI Y U None Y Large Amount

Light dust on floors; one pile of “material,” could be from remodeling 

activity
95

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

14 Residence 2 0 MI Y U None Y None Visible Pile of trash swept into center of room; no WTC dust

15 Outside 0 N None Visible Bulk sample from roof top courtyard,

15 Common 0 SI Y MS None Visible Dust visible in (and sampled from) cracks between tiles.

15 Residence 1 0 SI Y U O Y None Visible

15 Residence 2 0 SI N U O Y None Visible

16 Outside 0 N None Visible

16 Common 0 MI N C None Visible

16 Residence 1 0 MS None Visible

16 Residence 2 0 LI N Y O N No picture

17 Outside 0 N Slight Amount Dirty/messy, but doesn't look like WTC dust

17 Common 0 SI Y C None Visible

17 Residence 1 0 SI N Y C N None Visible

17 Residence 2 0 MI Y U C Y Slight Amount

18 Outside 0 N M Sample looks granular and sandy, not gray like WTC dust

18 Common 0 LI N MS None Visible Leaf track-in visible

18 Residence 1 0 MI N Y C N None Visible Window view of WTC site

18 Residence 2 0 LI N Y C N None Visible

19 Outside 0 N Moderate 

19 Common 0 SI N C None Visible

Visible in, and sampled from, sidewalk joint with building; sidewalk 

looked cleaner.

19 Residence 1 0 LI N Y O N None Visible

19 Residence 2 0 NI N Y O N No picture

20 Outside 0 N Unk Too distant to see surface dust

20 Common 0 SI N MS None Visible

20 Residence 1 0 NI N Y O N None Visible

20 Residence 2 0 SI N Y O N No picture

21 Outside 0 N None Visible

21 Common 0 SI N C None Visible

21 Residence 1 0 SI N Y C N None Visible

21 Residence 2 0 NI N Y C N None Visible
96

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

22 Outside 8 Y None Visible

22 Common 1 LI N C None Visible

Sidewalk/entrance to building and roof courtyard look clean, but 

there is a pile of material to sample on roof; location is unknown.

22 Residence 1 0 MI Y Y MS N None Visible

22 Residence 2 0 LI N Y C N None Visible

23 Outside 0 N None Visible

23 Common 0 SI N C None Visible

23 Residence 1 0 MI Y Y O N None Visible

23 Residence 2 0 MI N Y O N None Visible

24 Outside 0 N None Visible

24 Common 0 LI N MS None Visible

24 Residence 1 0 SI N Y O N None Visible

24 Residence 2 0 SI N Y C N None Visible

25 Outside 0 N None Visible

25 Common 0 NI N MS None Visible

25 Residence 1 0 NI N Y O N None Visible

25 Residence 2 0 SI N Y C N None Visible

26 Outside 0 N None Visible

26 Common 0 NI N MS None Visible Floor area sampled contained some broken tiles.

26 Residence 1 0 NI N Y O N None Visible

26 Residence 2 0 SI N Y O N None Visible

27 Outside 0 N None Visible

27 Common 0 MI N MS None Visible

27 Residence 1 0 LI N Y C N None Visible

27 Residence 2 0 SI N Y C N None Visible

28 Outside 0 None Visible

28 Common 0 LI Y C None Visible

Bulk sample from 4-inch wide strip between two different tiled areas; 

thick with granular/dusty/other material, not sure if any is WTC.

28 Residence 1 3 LI N U C N None Visible

28 Residence 2 0 MI N U C N None Visible

29 Outside 0 N None Visible Bulk sample from small pile at an inside corner of the building wall
97

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

29 Common 0 NI N C None Visible

29 Residence 1 0 SI N Y O N None Visible

29 Residence 2 0 SI Y Y O N None Visible

30 Outside 0 No picture

30 Common 0 No picture

30 Residence 1 0 SI N Y O N None Visible

30 Residence 2 0 MI N Y C N None Visible

31 Outside 0 None Visible

31 Common 0 NI N MS None Visible

31 Residence 1 0 NI N N MS Y None Visible

31 Residence 2 0 NI UNK Y O N None Visible

32 Outside 0 None Visible Trash visible on sidewalk

32 Common 0 NI N MS None Visible

32 Residence 1 0 NI N Y O N None Visible

32 Residence 2 0

33 Outside 0 None Visible

33 Common 0

33 Residence 1 0

33 Residence 2 0 NI Y Y O N None Visible

34 Outside 0 N None Visible

34 Common 0 NI N MS None Visible

34 Residence 1 0

34 Residence 2 0 UNK N Y O N None Visible
98

Summary of Residential Sampling Survey Form Results and Review of Photographs

(Abbreviations and terms used in the table are defined on the last page in this table.)

Event 

Number Location

Number of 

Broken 

Windows

Dust Visible 

Initially

Dust Visible 

Currently

Residence 

Occupied

Cleaning 

Method

Aggressive 

Sampling

Level of Dust 

in Photo Photo Comments

AA = asbestos abatement professionals

C = contractor

LI = large increase

M = moderate increase

MS = building management staff

N = no

NI = no Increase

O = owner/tenant

SI = slight increase over normal

UNK = unknown

Y = yes
99

Appendix C. Detailed Analytic Results
100

Results of Fiber Analyses

Results of fiber analyses in air and dust samples from 30 residential buildings (1–30) in lower 

Manhattan and 4 comparison buildings (31–34) above 59th Street. The range of values measured 

in the comparison buildings is shown in the summary of comparison areas above 59th Street.

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

Summary of Comparison Areas Above 59th Street

Outside <.001–0.001 NA ND–<.000043 Not Sampled Not Sampled Not Sampled

Common <.001–0.002 NA ND–0.000043 ND ND ND

Residences <.001–0.003 NA ND–0.000087 ND ND ND

Results for Individual Buildings Sampled in Lower Manhattan (Buildings 1–30)

1 Outside 0.001 ND <1 22

1 Common <.001 Not Sampled Not Sampled Not Sampled

1 Residence 1 0.006 <.001 0.000162 ND NA 20

1 Residence 2 <.001 ND NA 20

2 Outside 0.003 <1 1.2 28

2 Outside co-located Not Sampled Not Sampled Not Sampled 1.3 NA 25

2 Common 0.005 <.001 0.000255 ND NA 27

2 Residence 1 <.001 ND NA 25

2 Residence 2 0.002 ND NA 20

2 Window sill Not Sampled Not Sampled Not Sampled <1 <1 30

3 Outside <.001 Not Sampled Not Sampled Not Sampled

3 Res 2 co-located <.001 Not Sampled Not Sampled Not Sampled

3 Common <.001 Not Sampled Not Sampled Not Sampled

3 Residence 1 <.001 Not Sampled Not Sampled Not Sampled

3 Residence 2 <.001 Not Sampled Not Sampled Not Sampled

4 Outside 0.001 Not Sampled Not Sampled Not Sampled

4 Outside co-located <.001 Not Sampled Not Sampled Not Sampled

4 Common 0.001 ND <1 15

4 Common co-located 0.001 Not Sampled Not Sampled Not Sampled

4 Residence 1 <.001 ND <1 2

4 Residence 2 0.001 ND <1 5

5 Outside 0.002 3.4 NA 25
101

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

5 Outside co-located 0.003 Not Sampled Not Sampled Not Sampled

5 Common 0.002 Not Sampled Not Sampled Not Sampled

5 Residence 1 0.002 <1 <1 10

5 Residence 2 <.001 ND <1 20

6 Outside <.001 Not Sampled Not Sampled Not Sampled

6 Common <.001 ND <1 10

6 Res 2 co-located 0.002 Not Sampled Not Sampled Not Sampled

6 Residence 1 <.001 ND ND 15

6 Residence 2 <.001 ND ND 15

7 Outside <.001 ND 1.7 35

7 Common 0.001 ND ND 5

7 Residence 1 0.001 ND ND ND

7 Residence 2 <.001 ND ND 5

7 Window sill (R2) Not Sampled Not Sampled Not Sampled ND ND 40

8 Outside 0.001 Not Sampled Not Sampled Not Sampled

8 Common 0.002 ND ND ND

8 Residence 1 0.003 ND ND ND

8 Residence 2 0.002 ND ND ND

9 Outside <.001 Not Sampled Not Sampled Not Sampled

9 Common 0.001 ND ND 7

9 Common co-located 0.001 Not Sampled Not Sampled Not Sampled

9 Residence 1 0.001 ND <1 2

9 Residence 2 0.003 ND <1 5

10 Outside 0.001 ND ND ND

10 Common 0.002 ND 1.5 20

10 Common, TEM re-analysis <1

10 Residence 1 0.001 ND ND 15

10 Residence 2 0.001 ND ND 10

11 Outside <.001 Not Sampled Not Sampled Not Sampled

11 Common <.001 ND ND ND

11 Common co-located <.001 Not Sampled Not Sampled Not Sampled

11 Residence 1 <.001 ND <1 ND

11 Residence 2 <.001 ND 1.5 ND

12 Outside <.001 Not Sampled Not Sampled Not Sampled
102

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

12 Common <.001 ND ND ND

12 Residence 1 0.001 ND ND 5

12 Residence 2 <.001 ND ND 5

13 Outside 0.001 Not Sampled Not Sampled Not Sampled

13 Common 0.001 ND ND ND

13 Residence 1 0.003 ND ND 10

13 Residence 2 0.002 ND ND ND

14 Outside <.001 Not Sampled Not Sampled Not Sampled

14 Common 0.0013 ND ND 5

14 Residence 1 0.001 ND ND ND

14 Res 1 co-located <.001 Not Sampled Not Sampled Not Sampled

14 Residence 2 <.001 ND ND ND

15 Outside <.001 ND 1.9 72

15 Common 0.001 ND ND ND

15 Residence 1 <.001 ND <1 ND

15 Residence 2 <.001 ND ND 5

16 Outside <.001 ND ND 1

16 Common <.001 ND ND ND

16 Residence 1 Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled

16 Residence 2 <.001 ND ND ND

16 Res 2 co-located Not Sampled Not Sampled Not Sampled ND NA ND

16 Res 2 filter piece Not Sampled Not Sampled Not Sampled ND NA ND

17 Outside <.001 Not Sampled Not Sampled Not Sampled

17 Common <.001 ND ND 2

17 Residence 1 <.001 ND ND ND

17 Residence 2 <.001 ND ND ND

18 Outside <.001 ND ND 30

18 Common <.001 ND ND ND

18 Residence 1 0.002 ND ND 30

18 Residence 2 0.002 ND ND 35
103

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

19 Outside <.001 ND NA ND

19 Common overloaded <.006 ND ND ND

19 Residence 1 <.001 ND ND ND

19 Residence 2 <.001 ND ND ND

20 Outside <.001 Not Sampled Not Sampled Not Sampled

20 Outside co-located <.001 Not Sampled Not Sampled Not Sampled

20 Common <.001 ND ND ND

20 Residence 1 <.001 ND ND ND

20 Residence 2 <.001 ND ND ND

21 Outside <.001 Not Sampled Not Sampled Not Sampled

21 Common <.001 ND ND ND

21 Residence 1 <.001 ND ND ND

21 Residence 2 <.001 ND ND ND

22 Outside <.001 ND ND 7

22 Common 0.001 ND ND 3

22 Residence 1 <.001 ND ND 2

22 Residence 2 <.001 ND ND ND

22 Res 2 co-located <.001 Not Sampled Not Sampled Not Sampled

23 Outside <.001 Not Sampled Not Sampled Not Sampled

23 Common <.001 ND ND ND

23 Residence 1 <.001 ND ND ND

23 Residence 2 <.001 ND ND ND

24 Outside 0.002 ND ND 55

24 Common 0.001 ND <1 5

24 Residence 1 0.001 ND ND ND

24 Residence 2 0.005 <.001 0.000037 ND ND 10

24 Res 2 co-located 0.005 <.001 Not Sampled Not Sampled Not Sampled

25 Outside <.001 Not Sampled Not Sampled Not Sampled

25 Common <.001 ND ND 5

25 Residence 1 <.001 ND ND 5

25 Residence 2 0.001 ND ND ND

26 Outside 0.001 Not Sampled Not Sampled Not Sampled

26 Common 0.004 <.001 <0.00004 ND ND 5

26 Residence 1 0.012 <.001 <0.00004 ND ND ND
104

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

26 Residence 2 <.001 ND ND ND

27 Outside <.001 ND <1 15

27 Common <.001 ND <1 10

27 Residence 1 <.001 ND <1 10

27 Residence 2 <.001 ND ND 10

28 Outside <.001 ND ND 15

28 Common 0.001 ND ND 10

28 Residence 1 <.001 ND Insufficient Material ND

28 Residence 2 0.002 ND ND ND

29 Outside <.001 ND ND ND

29 Common <.001 ND ND ND

29 Residence 1 <.001 ND ND ND

29 Residence 2 <.001 ND ND ND

30 Outside Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled

30 Common Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled

30 Residence 1 <.001 ND ND ND

30 Residence 2 <.001 ND ND ND

Results for Comparison Buildings Sampled Above 59th Street (Buildings 31–34)

31 Outside <.001 Not Sampled Not Sampled Not Sampled

31 Outside co-located 0.001 0.000039 Not Sampled Not Sampled Not Sampled

31 Common <.001 ND ND ND

31 Residence 1 <.001 <0.000039 ND ND ND

31 Residence 2 <.001 <0.000038 ND ND ND

32 Outside <.001 <0.000039 Not Sampled Not Sampled Not Sampled

32 Common 0.002 <0.00004 ND ND ND

32 Residence 1 <.001 ND ND ND

32 Res 1 co-located 0.001 0.000087 Not Sampled Not Sampled Not Sampled

32 Residence 2 Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled

33 Outside Not Sampled Not Sampled Not Sampled Not Sampled

33 Common Not Sampled Not Sampled Not Sampled Not Sampled

33 Residence 1 Not Sampled Not Sampled Not Sampled Not Sampled

33 Residence 2 <.001 <0.000041 ND ND ND

34 Outside <.001 <0.000043 Not Sampled Not Sampled Not Sampled
105

Results From Air Samples Results From Dust Samples

Building 

Number Sample Location

Fibers in Air 

PCM (f/cc)

Asbestos in 

Air TEM (f/cc)

SVF in Air 

SEM (f/cc)

Asbestos in 

Dust PLM (%)

Asbestos in Dust 

TEM (%)

SVF in Dust 

PLM (%)

34 Common <.001 0.000043 ND ND ND

34 Residence 1 Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled

34 Residence 2 0.002 ND Insuf. Material ND

34 Res 2 co-located 0.003 <0.000047 Not Sampled Not Sampled Not Sampled

f/cc: fibers per cubic centimeter of air

NA: not analyzed

ND: not detected

PCM: phase contrast microscopy

PLM: polarized light microscopy

SEM: scanning electron microscopy

SVF: synthetic vitreous fibers

TEM: transmission electron microscopy

%: percent
106

Results of Mineral Analyses in Dust and Air

The following table shows the results of analyses of the minerals in settled dust and air samples for 30 

residential buildings in lower Manhattan (1–30) and 4 comparison buildings (31−34) above 59th Street. For 

each building, the table shows the highest estimated air concentration of mineral for each size fraction. In 

addition, estimated levels of each mineral in the settled surface dust are shown for each sampled location 

within a building.

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

Summary of Comparison Areas Above 59th Street

Air (μg/m3) PM100 ND ND ASN ND ND ND–3 J ND ND

Air (μg/m3) PM10 ND ND ASN ND ND ND–3 J ND ND

Air (μg/m3) PM4 ND ND ASN ND ND ND–5 J ND ND

Air (μg/m3) PM2.5 ND ND ASN ND ND ND–3 J ND ND

Settled surface dust 

(%) Common Area ND–1 J ND ND ND–0.4 J ND–0.05 J ND–3 J ND ND

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

Settled surface dust 

(%) Residence 1&2 ND–2 J ND ND ND–0.9 J ND–0.08 J 2–4 J ND–0.08 J ND–0.4 J

Results for Individual Buildings Sampled in Lower Manhattan (Buildings 1–30)

1 Air (μg/m3) PM100 ND ND ASN ND ND 6 J ND ND

1 Air (μg/m3) PM10 ND ND ASN ND ND 14 J ND ND

1 Air (μg/m3) PM4 ND ND ASN 6 J 84 J 12 J ND ND

1 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

1

Settled surface dust 

(%) Common area NS NS NS NS NS NS NS NS

1

Settled surface dust 

(%) Outdoor 27 J ND ND 15 J 6 J 14 J ND ND

1

Settled surface dust 

(%) Residence 1 19 J ND ND 18 J 2 J 30 J 0.3 J ND

1

Settled surface dust 

(%) Residence 2 31 J ND ND 21 J 6 J 4 J 0.05 J ND

2 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

2 Air (μg/m3

) PM10 ND ND ASN ND ND ND ND ND

2 Air (μg/m3) PM4 ND ND ASN ND ND 7J ND ND

2 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

2

Settled surface dust 

(%) Common area 1 J ND ND ND 2 J 14 J ND ND

2

Settled surface dust 

(%) Outdoor 21 J ND ND 19 J 3 J 27 J ND <0.03 J

2

Settled surface dust 

(%) Residence 1 3 J ND ND 2 J 0.9 J 6 J ND ND

2

Settled surface dust 

(%) Residence 2 23 J ND ND 15 J 4 J 9 J ND ND

3 Air (μg/m3

) PM100 6 J 15 J ASN 5 J 24 J 5 J 13 J ND

3 Air (μg/m3) PM10 5 J ND ASN 5 J 25 J 6 J ND ND

3 Air (μg/m3) PM4 6 J ND ASN 6 J 26 J 7 J ND ND

3 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS
107

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

3

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

3

Settled surface dust 

(%) Common NS NS NS NS NS NS NS NS

3

Settled surface dust 

(%) Residence 1 NS NS NS NS NS NS NS NS

3

Settled surface dust 

(%) Residence 2 NS NS NS NS NS NS NS NS

4 Air (μg/m3) PM100 4 J ND ASN 4 J 16 J 3 J 9 J 5 J

4 Air (μg/m3) PM10 4 J ND ASN 3 J 16 J 3 J ND 4 J

4 Air (μg/m3) PM4 6 J ND ASN 6 J 28 J 5 J 14 J 8 J

4 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

4

Settled surface dust 

(%) Common area ND ND ND 1 J 0.4 J 8 J ND ND

4

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

4

Settled surface dust 

(%) Residence 1 0.2 J ND ND 0.06 J 0.7 J 1 J ND ND

4

Settled surface dust 

(%) Residence 2 14 J ND ND 5 J 2 J 9 J ND 0.1 J

5 Air (μg/m3) PM100 ND ND ASN 14 J 95 J 14 J ND 14 J

5 Air (μg/m3) PM10 ND ND ASN ND ND 14 J ND ND

5 Air (μg/m3) PM4 ND ND ASN ND ND 15 J ND ND

5 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

5

Settled surface dust 

(%) Common area NS NS NS NS NS NS NS NS

5

Settled surface dust 

(%) Outdoor 23 J ND ND 8 J ND ND ND ND

5

Settled surface dust 

(%) Residence 1 2 J ND ND ND ND 9 J ND ND

5

Settled surface dust 

(%) Residence 2 11 J ND ND 4 J 0.5 J 2 J ND ND

6 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

6 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

6 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

6 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

6

Settled surface dust 

(%) Common area 17 J ND ND 10 J 3 J 20 J 0.6 J ND

6

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

6

Settled surface dust 

(%) Residence 1 27 J ND ND 17 J 8 J 13 J ND ND

6

Settled surface dust 

(%) Residence 2 24 J ND ND 15 J 4 J 4 J 0.03 J ND

7 Air (μg/m3) PM100 ND ND ASN 8 J 54 J 10 J ND ND

7 Air (μg/m3) PM10 ND ND ASN ND ND 11 J ND ND

7 Air (μg/m3) PM4 ND ND ASN ND ND 11 J ND ND

7 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

7

Settled surface dust 

(%) Common area 11 J ND ND 8 J 3 J 15 J 0.09 J 0.04 J

7

Settled surface dust 

(%) Outdoor 14 J ND ND 7 J 1 J 12 J ND 0.1 J

7

Settled surface dust 

(%) Residence 1 14 J ND ND 13 J 2 J 2 J ND ND
108

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

7

Settled surface dust 

(%) Residence 2 21 J ND ND 16 J 3 J 4 J ND 0.09 J

7

Settled surface dust 

(%) Residence 2-co 18 J ND ND 9 J 1 J 2 J ND ND

8 Air (μg/m3) PM100 ND ND ASN 7 J ND 10 J ND ND

8 Air (μg/m3) PM10 ND ND ASN ND ND 9 J ND ND

8 Air (μg/m3) PM4 ND ND ASN 6 J ND 12 J 43 J 19 J

8 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

8

Settled surface dust 

(%) Common area 19 J ND ND 9 J 2 J 15 J ND ND

8

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

8

Settled surface dust 

(%) Residence 1 15 J ND ND 10 J 3 J 17 J ND ND

8

Settled surface dust 

(%) Residence 2 28 J ND ND 21 J 4 J 6 J ND ND

9 Air (μg/m3) PM100 ND ND ASN ND ND 3 J ND ND

9 Air (μg/m3) PM10 ND ND ASN 4 J ND 6 J ND ND

9 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

9 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

9

Settled surface dust 

(%) Common area 25 J ND ND 9 J 4 J 16 J 0.09 J 0.06 J

9

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

9

Settled surface dust 

(%) Residence 1 10 J ND ND 2 J 0.9 J 5 J ND ND

9

Settled surface dust 

(%) Residence 2 4 J ND ND ND ND 2 J ND ND

10 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

10 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

10 Air (μg/m3) PM4 ND ND ASN 8 J ND ND ND ND

10 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

10

Settled surface dust 

(%) Common area 2 J ND ND 3 J ND 1 J ND ND

10

Settled surface dust 

(%) Common area-co NS NS NS NS NS NS NS NS

10

Settled surface dust 

(%) Outdoor 21 J ND ND 14 J 3 J 5 J 0.09 J 0.05 J

10

Settled surface dust 

(%) Residence 1 3 J ND ND ND 0.06 J ND ND ND

10

Settled surface dust 

(%) Residence 2 2 J ND ND ND ND 0.8 J ND 0.04 J

11 Air (μg/m3) PM100 NS NS NS NS NS NS NS NS

11 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

11 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

11 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

11

Settled surface dust 

(%) Common area 2 J ND ND ND ND 1 J ND ND

11

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

11

Settled surface dust 

(%) Residence 1 0.2 J ND ND 0.02 J ND 2 J ND ND

11

Settled surface dust 

(%) Residence 2 0.07 J ND ND ND ND ND ND ND
109

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

12 Air (μg/m3) PM100 NS NS NS NS NS NS NS NS

12 Air (μg/m3) PM10 3 J ND ASN 5 J 18 J 4 J 8 J 5 J

12 Air (μg/m3) PM4 5 J ND ASN 7 J 28 J 6 J 15 J 7 J

12 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

12

Settled surface dust 

(%) Common area 4 J ND ND 2 J 3 J 1 J ND ND

12

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

12

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 0.3 J ND ND

12

Settled surface dust 

(%) Residence 2 0.4 J ND ND 0.09 J 0.06 J 0.8 J ND ND

13 Air (μg/m3) PM100 5 J ND ASN 5 J 16 J 3 J ND ND

13 Air (μg/m3) PM10 4 J ND ASN 5 J 16 J 3 J ND ND

13 Air (μg/m3) PM4 7 J ND ASN 10 J 26 J 5 J ND ND

13 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

13

Settled surface dust 

(%) Common area 0.05 J ND ND 0.3 J 0.04 J 1 J ND ND

13

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

13

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 1 J ND ND

13

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 0.8 J ND ND

14 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

14 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

14 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

14 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

14

Settled surface dust 

(%) Common area 0.03 J ND ND ND ND 2 J ND 0.04 J

14

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

14

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

14

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 0.08 J ND ND

15 Air (μg/m3) PM100 8 J ND ASN 3 J 18 J ND ND ND

15 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

15 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

15 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

15

Settled surface dust 

(%) Common area 0.4 J ND ND 0.02 J ND 1 J ND ND

15

Settled surface dust 

(%) Outdoor 1 J ND ND ND 0.3 J 2 J ND ND

15

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 1 J ND ND

15

Settled surface dust 

(%) Residence 2 ND ND ND ND ND ND ND ND

16 Air (μg/m3) PM100 4 J ND ASN 3 J 17 J 3 J ND ND

16 Air (μg/m3) PM10 ND ND ASN ND ND 4 J ND ND

16 Air (μg/m3) PM4 18 J ND ASN 5 J 27 J 7 J ND ND
110

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

16 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

16

Settled surface dust 

(%) Common area ND ND ND ND ND 0.09 J ND ND

16

Settled surface dust 

(%) Outdoor 3 J ND ND 1 J 0.6 J 0.04 J 0.06 J 0.04 J

16

Settled surface dust 

(%) Residence 1 NS NS NS NS NS NS NS NS

16

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 0.9 J ND ND

16

Settled surface dust 

(%) R2 filter piece 2 J ND ND 0.3 J 0.4 J 1 J ND ND

17 Air (μg/m3) PM100 NS NS NS NS NS NS NS NS

17 Air (μg/m3) PM10 12 J ND ASN 4 J 17 J 6 J ND 5 J

17 Air (μg/m3) PM4 5 J ND ASN 5 J 27 J 6 J 15 J ND

17 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

17

Settled surface dust 

(%) Common area 2 J ND ND ND ND 1 J 0.06 J ND

17

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

17

Settled surface dust 

(%) Residence 1 0.9 J ND ND ND 0.05 J 2 J 0.05 J 0.03 J

17

Settled surface dust 

(%) Residence 2 1 J ND ND 0.8 J ND 1 J ND ND

18 Air (μg/m3) PM100 3 J ND ASN ND ND ND ND ND

18 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

18 Air (μg/m3) PM4 5 J ND ASN ND ND 5 J ND ND

18 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

18

Settled surface dust 

(%) Common area 0.9 J ND ND ND ND ND ND ND

18

Settled surface dust 

(%) Outdoor 7 J ND ND 1 J ND ND 0.2 J ND

18

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 0.3 J ND ND

18

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 1 J ND ND

19 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

19 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

19 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

19 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

19

Settled surface dust 

(%) Common area 1 J ND ND 0.08 J 0.05 J 1 J ND ND

19

Settled surface dust 

(%) Outdoor 5 J ND ND 1 J 0.6 J 1 J 0.09 J 0.04 J

19

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 1 J ND ND

19

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 2 J ND ND

20 Air (μg/m3) PM100 3 J ND ASN 3 J 16 J 3 J ND ND

20 Air (μg/m3) PM10 3 J ND ASN 3 J 16 J 4 J ND ND

20 Air (μg/m3) PM4 5 J ND ASN 5 J 29 J 6 J ND ND

20 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

20

Settled surface dust 

(%) Common area ND ND ND ND ND 0.07 J ND 0.04 J
111

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

20

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

20

Settled surface dust 

(%) Residence 1 0.05 J ND ND ND ND 1 J ND ND

20

Settled surface dust 

(%) Residence 2 0.9 J ND ND 0.6 J 0.09 J 1 J ND 0.05 J

21 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

21 Air (μg/m3) PM10 R R R R R R R R

21 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

21 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

21

Settled surface dust 

(%) Common area 0.9 J ND ND ND ND 2 J ND ND

21

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

21

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

21

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 1 J ND ND

22 Air (μg/m3) PM100 13 J ND ASN ND ND ND ND ND

22 Air (μg/m3) PM10 3 J ND ASN ND ND ND ND ND

22 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

22 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

22

Settled surface dust 

(%) Common area 14 J ND ND 1 J 0.4 J ND ND ND

22

Settled surface dust 

(%) Outdoor 26 J ND ND 2 J 0.8 J 0.03 J 0.07 J ND

22

Settled surface dust 

(%) Residence 1 2 J ND ND 0.07 J 0.08 J 1 J ND ND

22

Settled surface dust 

(%) Residence 2 0.6 J ND ND ND ND 2 J ND ND

23 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

23 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

23 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

23 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

23

Settled surface dust 

(%) Common area 2 J ND ND 0.04 J 0.05 J 0.9 J ND ND

23

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

23

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

23

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 1 J ND ND

24 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

24 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

24 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

24 Air (μg/m3) PM2.5 3 J ND ASN ND ND ND ND ND

24

Settled surface dust 

(%) Common area 0.03 J ND ND ND ND ND ND ND

24

Settled surface dust 

(%) Outdoor 2 J ND ND 0.8 J 0.07 J ND 0.05 J 0.04 J

24

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

24

Settled surface dust 

(%) Residence 2 ND ND ND ND ND ND ND ND
112

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

25 Air (μg/m3) PM100 ND ND ASN ND ND 3 J ND ND

25 Air (μg/m3) PM10 R R R R R R R R

25 Air (μg/m3) PM4 ND ND ASN ND ND 4 J ND ND

25 Air (μg/m3) PM2.5 ND ND ASN ND ND 3 J ND ND

25

Settled surface dust 

(%) Common area ND ND ND ND ND 2 J ND ND

25

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

25

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

25

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 2 J ND ND

26 Air (μg/m3) PM100 8 J ND ASN ND ND ND ND ND

26 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

26 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

26 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

26

Settled surface dust 

(%) Common area 0.7 J ND ND 2 J 0.6 J 2 J 0.07 J ND

26

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

26

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

26

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 0.05 J ND ND

27 Air (μg/m3) PM100 3 J ND ASN ND ND ND ND ND

27 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

27 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

27 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

27

Settled surface dust 

(%) Common area 0.04 J ND ND 0.02 J ND 0.1 J ND ND

27

Settled surface dust 

(%) Outdoor 4 J ND ND 1 J 0.8 J 0.04 J 0.07 J ND

27

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 0.6 J ND ND

27

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 1 J ND ND

28 Air (μg/m3) PM100 3 J ND ASN ND ND 3 J ND 4 J

28 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

28 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

28 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

28

Settled surface dust 

(%) Common area ND ND ND ND ND 1 J ND ND

28

Settled surface dust 

(%) Outdoor 8 J ND ND 3 J 2 J 0.3 J 0.09 J ND

28

Settled surface dust 

(%) Residence 1 ND ND ND ND ND ND ND ND

28

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 1 J ND ND

29 Air (μg/m3) PM100 4 J ND ASN ND ND ND ND ND

29 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

29 Air (μg/m3) PM4 19 J ND ASN ND ND 5 J ND ND
113

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

29 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

29

Settled surface dust 

(%) Common area 1 J ND ND 0.09 J 0.06 J 2 J ND ND

29

Settled surface dust 

(%) Outdoor 8 J ND ND 3 J 2 J 2 J 0.3 J 0.07 J

29

Settled surface dust 

(%) Residence 1 0.2 J ND ND ND ND 1 J ND ND

29

Settled surface dust 

(%) Residence 2 ND ND ND ND ND ND ND ND

30 Air (μg/m3) PM100 NS NS NS NS NS NS NS NS

30 Air (μg/m3) PM10 3 J ND ASN ND ND 3 J ND ND

30 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

30 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

30

Settled surface dust 

(%) Common area NS NS NS NS NS NS NS NS

30

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

30

Settled surface dust 

(%) Residence 1 1 J ND ND ND 0.9 J 4 J 0.06 J 0.05 J

30

Settled surface dust

(%) Residence 2 0.6 J ND ND 0.4 J 0.4 J 4 J ND ND

Results for Individual Comparison Buildings Sampled Above 59th Street (Buildings 31–34)

31 Air (μg/m3) PM100 NS NS NS NS NS NS NS NS

31 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

31 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

31 Air (μg/m3) PM2.5 NS NS NS NS NS NS NS NS

31

Settled surface dust 

(%) Common area 1 J ND ND 0.03 J 0.05 J 2 J ND 0.04 J

31

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

31

Settled surface dust 

(%) Residence 1 ND ND ND ND ND 2 J ND ND

31

Settled surface dust 

(%) Residence 2 ND ND ND ND ND ND ND ND

32 Air (μg/m3) PM100 ND ND ASN ND ND 3 J ND ND

32 Air (μg/m3) PM10 ND ND ASN ND ND 3 J ND ND

32 Air (μg/m3) PM4 ND ND ASN ND ND 5 J ND ND

32 Air (μg/m3) PM2.5 ND ND ASN ND ND 3 J ND ND

32

Settled surface dust 

(%) Common area 1 J ND ND 0.4 J ND 3J ND ND

32

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

32

Settled surface dust 

(%) Residence 1 2 J ND ND 0.9 J 0.08 J 4 J 0.08 J 0.4 J

32

Settled surface dust 

(%) Residence 2 NS NS NS NS NS NS NS NS

33 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

33 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

33 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

33 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

33

Settled surface dust 

(%) Common area NS NS NS NS NS NS NS NS
114

Building 

Number Sample Type

Method or 

Location Quartz Cristobalite Tridymite Calcite Portlandite Gypsum Mica Halite

33

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

33

Settled surface dust 

(%) Residence 1 NS NS NS NS NS NS NS NS

33

Settled surface dust 

(%) Residence 2 1 J ND ND ND 0.08 J 2 J ND ND

34 Air (μg/m3) PM100 ND ND ASN ND ND ND ND ND

34 Air (μg/m3) PM10 ND ND ASN ND ND ND ND ND

34 Air (μg/m3) PM4 ND ND ASN ND ND ND ND ND

34 Air (μg/m3) PM2.5 ND ND ASN ND ND ND ND ND

34

Settled surface dust 

(%) Common area ND ND ND ND ND ND ND ND

34

Settled surface dust 

(%) Outdoor NS NS NS NS NS NS NS NS

34

Settled surface dust 

(%) Residence 1 NS NS NS NS NS NS NS NS

34

Settled surface dust 

(%) Residence 2 ND ND ND ND ND 3 J ND ND

ASN: Analytical sensitivity not available. Mineral was not detected at any measured location using the 

associated method, analytical sensitivity is not known.

Detect: Mineral was detected above the analytical sensitivity in at least one of the measured locations 

of the building using the associated method.

J: Estimated value. Due to inconsistencies during sample collection/analysis, the result is only an estimate of 

the actual value. The actual value could be higher or lower than the value shown.

ND: Not detected. Mineral was not detected at any measured location using the associated method.

NS: Not sampled. The associated method was not used at any of the measured locations in the building.

R: Result was rejected. Due to inconsistencies during sample collection/analysis, the result values for the 

sample were rejected.

μg/m3: microgram per cubic meter of air.
115

Mineral Analyses in Air

Estimated levels of minerals in air for samples from 30 residential buildings (1–30) in lower 

Manhattan and 4 comparison residential buildings (31–34) above 59th Street are shown in the 

following table. The estimated air concentration of each mineral by size fraction is shown for each 

area sampled. Typically, samples were obtained from an outdoor area, an indoor common area, 

and two residences. In addition, co-located samples were obtained from some locations. 

However, due to inconsistencies during sample collection or analysis, the specific sampling 

location within the building is not noted.

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

Summary of Comparison Areas Above 59th Street

PM100 -- -- -- -- -- ND–3 J -- --

PM10 -- -- -- -- -- ND–3 J -- --

PM4 -- -- -- -- -- ND–5 J -- --

PM2.5 -- -- -- -- -- ND–3 J -- --

Results for Individual Buildings Sampled in Lower Manhattan (Buildings 1–30)

1 PM100 882 -- -- -- -- -- 6 J -- --

1 PM100 830 -- -- -- -- -- -- -- --

1 PM100 818 -- -- -- -- -- -- -- --

1 PM100 892 -- -- -- -- -- -- -- --

1 PM10 861 -- -- -- -- -- -- -- --

1 PM10 835 -- -- -- -- -- 7 J -- --

1 PM10 838 -- -- -- -- -- 14 J -- --

1 PM10 899 -- -- -- -- -- 8 J -- --

1 PM4 809 -- -- -- -- 84 J 10 J -- --

1 PM4 813 -- -- -- -- -- 12 J -- --

1 PM4 820 -- -- -- 6 J 68 J 10 J -- --

1 PM4 837 -- -- -- -- -- -- -- --

2 PM100 1229 -- -- -- -- -- -- -- --

2 PM100 1162 -- -- -- -- -- -- -- --

2 PM100 766 -- -- -- -- -- -- -- --

2 PM100 1240 -- -- -- -- -- -- --

2 PM10 1194 -- -- -- -- -- -- -- --

2 PM10 1168 -- -- -- -- -- -- -- --

2 PM10 1390 -- -- -- -- -- -- -- --

2 PM10 1216 -- -- -- -- -- -- -- --

2 PM4 757 -- -- -- -- -- 7J -- --

2 PM4 717 -- -- -- -- -- -- -- --

2 PM4 849 -- -- -- -- -- -- -- --
116

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

2 PM4 762 -- -- -- -- -- -- -- --

3 PM100 868 -- -- -- -- -- 5 J -- --

3 PM100 821 6 J 15 J -- 5 J 24 J 5 J 13 J --

3 PM100 756 -- -- -- -- -- 5 J -- --

3 PM100 761 -- -- -- -- -- -- -- --

3 PM10 858 -- -- -- -- -- 6 J -- --

3 PM10 815 5 J -- -- 5J 25 J 5 J -- --

3 PM10 765 -- -- -- -- -- 5 J -- --

3 PM10 783 -- -- -- -- -- -- -- --

3 PM4 814 5 J -- -- -- -- 6 J -- --

3 PM4 824 6 J -- -- 6 J 26 J 7 J -- --

3 PM4 841 -- -- -- -- -- 5 J -- --

3 PM4 823 -- -- -- -- -- -- -- --

4 PM100 1230 -- -- -- -- -- 3 J -- --

4 PM100 1289 4 J -- -- 4 J 16 J 3 J 9 J 5J

4 PM100 1278 -- -- -- -- -- -- -- --

4 PM100 1221 -- -- -- -- -- 3 J -- 5J

4 PM10 1218 -- -- -- -- 16 J 3 J -- --

4 PM10 1415 4 J -- -- 3 J 16 J 3 J -- 4J

4 PM10 1294 -- -- -- -- -- 3 J -- --

4 PM10 1201 -- -- -- -- -- -- -- --

4 PM4 751 -- -- -- -- 27J 5J -- --

4 PM4 793 6 J -- -- 6J 28J 5J 14 J 8 J

4 PM4 804 -- -- -- -- -- 5 J -- --

4 PM4 757 -- -- -- -- -- -- -- --

5 PM100 783 -- -- -- 14 J 95 J 14 J -- 14 J

5 PM100 786 -- -- -- -- -- -- -- --

5 PM100 804 -- -- -- -- -- -- -- --

5 PM100 800 -- -- -- -- -- -- -- --

5 PM10 780 -- -- -- -- -- -- -- --

5 PM10 797 -- -- -- -- -- -- -- --

5 PM10 846 -- -- -- -- -- 14 J -- --

5 PM10 789 -- -- -- -- -- -- -- --

5 PM4 817 -- -- -- -- -- -- -- --

5 PM4 664 -- -- -- -- -- -- -- --

5 PM4 813 -- -- -- -- -- 9 J -- --

5 PM4 813 -- -- -- -- -- 15 J -- --

6 PM100 1241 -- -- -- -- -- -- -- --
117

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

6 PM100 1212 -- -- -- -- -- -- -- --

6 PM100 1238 -- -- -- -- -- -- -- --

6 PM100 NS NS NS NS NS NS NS NS NS

6 PM10 1226 -- -- -- -- -- -- -- --

6 PM10 1197 -- -- -- -- -- -- -- --

6 PM10 1252 -- -- -- -- -- -- -- --

6 PM10 1254 -- -- -- -- -- -- -- --

6 PM4 775 -- -- -- -- -- -- -- --

6 PM4 762 -- -- -- -- -- -- -- --

6 PM4 775 -- -- -- -- -- -- -- --

6 PM4 772 -- -- -- -- -- -- -- --

7 PM100 1277 -- -- -- -- -- -- -- --

7 PM100 1260 -- -- -- 8 J 54 J 10 J -- --

7 PM100 1243 -- -- -- -- -- -- -- --

7 PM100 1213 -- -- -- -- -- -- -- --

7 PM10 1227 -- -- -- -- -- -- -- --

7 PM10 1225 -- -- -- -- -- 11 J -- --

7 PM10 1240 -- -- -- -- -- -- -- --

7 PM10 1231 -- -- -- -- -- -- -- --

7 PM4 787 -- -- -- -- -- -- -- --

7 PM4 784 -- -- -- -- -- 10 J -- --

7 PM4 765 -- -- -- -- -- 11 J -- --

7 PM4 748 -- -- -- -- -- -- -- --

8 PM100 1213 -- -- -- 7 J -- 10 J -- --

8 PM100 1254 -- -- -- -- -- 6 J -- --

8 PM100 1223 -- -- -- -- -- 7 J -- --

8 PM100 1206 -- -- -- -- -- -- -- --

8 PM100 1175 -- -- -- -- -- -- -- --

8 PM100 1259 -- -- -- -- -- -- -- --

8 PM10 1188 -- -- -- -- -- 9 J -- --

8 PM10 1223 -- -- -- -- -- 6 J -- --

8 PM10 1172 -- -- -- -- -- -- -- --

8 PM10 1256 -- -- -- -- -- -- -- --

8 PM4 757 -- -- -- -- -- 12 J -- --

8 PM4 784 -- -- -- 6 J -- 10 J -- --

8 PM4 738 -- -- -- -- -- -- -- --

8 PM4 777 -- -- -- -- -- 10J 43J 19 J

9 PM100 1210 -- -- -- -- -- -- -- --

9 PM100 1218 -- -- -- -- -- 3 J -- --
118

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

9 PM100 NS NS NS NS NS NS NS NS NS

9 PM100 NS NS NS NS NS NS NS NS NS

9 PM10 1203 -- -- -- -- -- -- -- --

9 PM10 1217 -- -- -- 4 J -- 6 J -- --

9 PM10 1231 -- -- -- -- -- -- -- --

9 PM10 1131 -- -- -- -- -- -- -- --

9 PM4 776 -- -- -- -- -- -- -- --

9 PM4 782 -- -- -- -- -- -- -- --

9 PM4 763 -- -- -- -- -- -- -- --

9 PM4 781 -- -- -- -- -- -- -- --

10 PM100 1201 -- -- -- -- -- -- -- --

10 PM100 1225 -- -- -- -- -- -- -- --

10 PM100 1220 -- -- -- -- -- -- -- --

10 PM100 1226 -- -- -- -- -- -- -- --

10 PM10 1181 -- -- -- -- -- -- -- --

10 PM10 1202 -- -- -- -- -- -- -- --

10 PM10 1227 -- -- -- -- -- -- -- --

10 PM10 1224 -- -- -- -- -- -- -- --

10 PM4 757 -- -- -- -- -- -- -- --

10 PM4 766 -- -- -- -- -- -- -- --

10 PM4 762 -- -- -- 8 J -- -- -- --

10 PM4 767 -- -- -- -- -- -- -- --

11 PM100 NS NS NS NS NS NS NS NS NS

11 PM100 NS NS NS NS NS NS NS NS NS

11 PM100 NS NS NS NS NS NS NS NS NS

11 PM100 NS NS NS NS NS NS NS NS NS

11 PM10 1305 -- -- -- -- -- -- -- --

11 PM10 1301 -- -- -- -- -- -- -- --

11 PM10 1337 -- -- -- -- -- -- -- --

11 PM10 1237 -- -- -- -- -- -- -- --

11 PM4 832 -- -- -- -- -- -- -- --

11 PM4 806 -- -- -- -- -- -- -- --

11 PM4 834 -- -- -- -- -- -- -- --

11 PM4 779 -- -- -- -- -- -- -- --

12 PM100 NS NS NS NS NS NS NS NS NS

12 PM100 NS NS NS NS NS NS NS NS NS

12 PM100 NS NS NS NS NS NS NS NS NS

12 PM100 NS NS NS NS NS NS NS NS NS

12 PM10 1412 3 J -- -- 3 J 14 J 3 J -- --
119

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

12 PM10 1315 3 J -- -- 5 J 18 J 4 J 8 J 5 J

12 PM10 1337 3 J -- -- 3 J 17 J 3 J -- 5 J

12 PM10 1553 R R R R R R R R

12 PM10 1479 R R R R R R R R

12 PM4 925 4 J -- -- 4 J 22 J 4 J -- --

12 PM4 828 5 J -- -- 7 J 28 J 6 J 15 J 7 J

12 PM4 948 R R R R R R R R

12 PM4 932 R R R R R R R R

13 PM100 1281 -- -- -- -- -- 3 J -- --

13 PM100 1300 -- -- -- -- -- -- -- --

13 PM100 1298 -- -- -- -- -- -- -- --

13 PM100 1284 5 J -- -- 5 J 16 J 3 J -- --

13 PM100 1211 -- -- -- -- -- -- -- --

13 PM100 1203 -- -- -- -- -- -- -- --

13 PM100 1184 -- -- -- -- -- -- -- --

13 PM10 1263 -- -- -- -- -- 3 J -- --

13 PM10 1325 4 J -- -- 5 J 16 J 3 J -- --

13 PM10 1223 -- -- -- -- -- -- -- --

13 PM10 1205 -- -- -- -- -- -- -- --

13 PM4 802 -- -- -- 5 J -- 5 J -- --

13 PM4 818 7 J -- -- 10 J 26 J 5 J -- --

13 PM4 762 -- -- -- -- -- -- -- --

13 PM4 761 -- -- -- -- -- -- -- --

14 PM100 1151 -- -- -- -- -- -- -- --

14 PM100 1169 -- -- -- -- -- -- -- --

14 PM100 1166 -- -- -- -- -- -- -- --

14 PM100 1142 -- -- -- -- -- -- -- --

14 PM100 1171 -- -- -- -- -- -- -- --

14 PM100 1149 -- -- -- -- -- -- -- --

14 PM10 1134 -- -- -- -- -- -- -- --

14 PM10 1138 -- -- -- -- -- -- -- --

14 PM10 1155 -- -- -- -- -- -- -- --

14 PM10 1179 -- -- -- -- -- -- -- --

14 PM10 1161 -- -- -- -- -- -- -- --

14 PM4 719 -- -- -- -- -- -- -- --

14 PM4 731 -- -- -- -- -- -- -- --

14 PM4 732 -- -- -- -- -- -- -- --

14 PM4 730 -- -- -- -- -- -- -- --

15 PM100 1219 -- -- -- -- -- -- -- --
120

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

15 PM100 1199 8 J -- -- 3 J 18 J -- -- --

15 PM100 1211 -- -- -- -- -- -- -- --

15 PM100 1156 -- -- -- -- -- -- -- --

15 PM10 1218 -- -- -- -- -- 3 J -- --

15 PM10 1115 R R R R R R R R

15 PM10 1212 -- -- -- -- -- -- -- --

15 PM10 1225 -- -- -- -- -- -- -- --

15 PM10 1171 -- -- -- -- -- -- -- --

15 PM4 783 -- -- -- -- -- 5 J -- --

15 PM4 778 -- -- -- -- -- -- -- --

15 PM4 766 -- -- -- -- -- -- -- --

15 PM4 751 -- -- -- -- -- -- -- --

16 PM100 1254 -- -- -- -- -- 3 J -- --

16 PM100 1225 4 J -- -- 3 J 17 J 3 J -- --

16 PM100 1217 -- -- -- -- -- -- -- --

16 PM10 1269 -- -- -- -- -- 4 J -- --

16 PM10 1228 -- -- -- -- -- 4 J -- --

16 PM10 1210 -- -- -- -- -- -- -- --

16 PM4 808 -- -- -- -- -- 7 J -- --

16 PM4 774 -- -- -- -- -- 5 J -- --

16 PM4 769 18 J -- -- 5 J 27 J 7 J -- --

16 PM4 769 -- -- -- -- -- -- -- --

17 PM10 1306 -- -- -- -- -- 4 J -- --

17 PM10 1469 3 J -- -- 3 J 16 J 3 J -- 4 J

17 PM10 1250 -- -- -- -- -- -- -- --

17 PM10 1259 -- -- -- -- -- 3 J -- --

17 PM10 1293 12 J -- -- 4 J 17 J 6 J -- 5 J

17 PM4 844 -- -- -- -- -- 5 J -- --

17 PM4 816 5 J -- -- 5 J 27 J 6 J 15 J --

17 PM4 786 -- -- -- -- -- -- -- --

17 PM4 786 -- -- -- -- -- 5 J -- --

17 PM4 803 -- -- -- -- 26 J 6 J -- --

18 PM100 1277 -- -- -- -- -- -- -- --

18 PM100 1247 3 J -- -- -- -- -- -- --

18 PM100 1241 -- -- -- -- -- -- -- --

18 PM100 1265 -- -- -- -- -- -- -- --

18 PM100 1177 -- -- -- -- -- -- -- --

18 PM10 1234 -- -- -- -- -- -- -- --

18 PM10 1269 -- -- -- -- -- -- -- --
121

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

18 PM10 1258 -- -- -- -- -- -- -- --

18 PM10 1268 -- -- -- -- -- -- -- --

18 PM10 1196 -- -- -- -- -- 3 J -- --

18 PM4 791 -- -- -- -- -- -- -- --

18 PM4 780 -- -- -- -- -- -- -- --

18 PM4 785 5 J -- -- -- -- -- -- --

18 PM4 778 -- -- -- -- -- -- -- --

18 PM4 735 -- -- -- -- -- 5 J -- --

19 PM100 1275 -- -- -- -- -- -- -- --

19 PM100 1288 -- -- -- -- -- -- -- --

19 PM100 1291 -- -- -- -- -- -- -- --

19 PM100 1215 -- -- -- -- -- -- -- --

19 PM10 1270 -- -- -- -- -- -- -- --

19 PM10 1296 -- -- -- -- -- -- -- --

19 PM10 1286 -- -- -- -- -- -- -- --

19 PM10 1218 R R R R R R R R

19 PM4 796 -- -- -- -- -- -- -- --

19 PM4 819 -- -- -- -- -- -- -- --

19 PM4 822 -- -- -- -- -- -- -- --

19 PM4 761 R R R R R R R R

20 PM100 1278 -- -- -- -- -- 3 J -- --

20 PM100 1226 -- -- -- 3 J 16 J 3 J -- --

20 PM100 1412 -- -- -- -- -- 3 J -- --

20 PM100 1417 -- -- -- -- -- 3 J -- --

20 PM100 1366 3 J -- -- -- -- 3 J -- --

20 PM10 1282 -- -- -- -- -- 3 J -- --

20 PM10 1226 -- -- -- 3 J 16 J -- -- --

20 PM10 1407 -- -- -- -- -- -- -- --

20 PM10 1357 3 J -- -- 3 J -- 4 J -- --

20 PM4 792 -- -- -- -- -- 6 J -- --

20 PM4 753 5 J -- -- 5 J 29 J 5 J -- --

20 PM4 891 -- -- -- -- -- -- -- --

20 PM4 842 5 J -- -- 5 J -- 5 J -- --

21 PM100 1227 -- -- -- -- -- -- -- --

21 PM100 1238 -- -- -- -- -- -- -- --

21 PM100 1203 -- -- -- -- -- -- -- --

21 PM100 1218 -- -- -- -- -- -- -- --

21 PM10 1248 R R R R R R R R

21 PM10 1256 R R R R R R R R
122

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

21 PM10 1212 R R R R R R R R

21 PM10 1241 R R R R R R R R

21 PM4 776 -- -- -- -- -- -- -- --

21 PM4 780 -- -- -- -- -- -- -- --

21 PM4 780 -- -- -- -- -- -- -- --

21 PM4 750 -- -- -- -- -- -- -- --

21 PM4 771 -- -- -- -- -- 5 J -- --

21 PM2.5 1236 -- -- -- -- -- -- -- --

21 PM2.5 1249 -- -- -- -- -- -- -- --

21 PM2.5 1211 -- -- -- -- -- -- -- --

21 PM2.5 1238 -- -- -- -- -- -- -- --

22 PM100 1336 5 J -- -- -- -- -- -- --

22 PM100 1385 13 J -- -- -- -- -- -- --

22 PM100 1365 7 J -- -- -- -- -- -- --

22 PM100 1364 -- -- -- -- -- -- -- --

22 PM100 1261 -- -- -- -- -- -- -- --

22 PM10 1346 3 J -- -- -- -- -- -- --

22 PM10 1389 -- -- -- -- -- -- -- --

22 PM10 1361 -- -- -- -- -- -- -- --

22 PM10 1383 -- -- -- -- -- -- -- --

22 PM10 1271 -- -- -- -- -- -- -- --

22 PM4 870 -- -- -- -- -- -- -- --

22 PM4 872 -- -- -- -- -- -- -- --

22 PM4 863 -- -- -- -- -- -- -- --

22 PM4 787 -- -- -- -- -- -- -- --

22 PM2.5 1343 -- -- -- -- -- -- -- --

22 PM2.5 1334 -- -- -- -- -- -- -- --

22 PM2.5 1354 -- -- -- -- -- -- -- --

22 PM2.5 1252 -- -- -- -- -- -- -- --

23 PM100 1546 -- -- -- -- -- -- -- --

23 PM100 1626 -- -- -- -- -- -- -- --

23 PM100 1554 -- -- -- -- -- -- -- --

23 PM100 1550 -- -- -- -- -- -- -- --

23 PM10 1578 -- -- -- -- -- -- -- --

23 PM10 1596 -- -- -- -- -- -- -- --

23 PM10 1568 -- -- -- -- -- -- -- --

23 PM10 1592 -- -- -- -- -- -- -- --

23 PM10 1612 -- -- -- -- -- -- -- --

23 PM4 991 -- -- -- -- -- -- -- --

23 PM4 1012 -- -- -- -- -- -- -- --
123

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

23 PM4 978 -- -- -- -- -- -- -- --

23 PM4 1014 -- -- -- -- -- -- -- --

23 PM2.5 1548 -- -- -- -- -- -- -- --

23 PM2.5 1009 -- -- -- -- -- -- -- --

23 PM2.5 1544 -- -- -- -- -- -- -- --

23 PM2.5 1584 -- -- -- -- -- -- -- --

24 PM100 1467 -- -- -- -- -- -- -- --

24 PM100 1471 -- -- -- -- -- -- -- --

24 PM100 1424 -- -- -- -- -- -- -- --

24 PM100 1490 -- -- -- -- -- -- -- --

24 PM100 1485 -- -- -- -- -- -- -- --

24 PM10 1475 -- -- -- -- -- -- -- --

24 PM10 1427 -- -- -- -- -- -- -- --

24 PM10 1482 -- -- -- -- -- -- -- --

24 PM10 1481 -- -- -- -- -- -- -- --

24 PM4 920 -- -- -- -- -- -- -- --

24 PM4 891 -- -- -- -- -- -- -- --

24 PM4 880 -- -- -- -- -- -- -- --

24 PM4 929 -- -- -- -- -- -- -- --

24 PM4 920 -- -- -- -- -- -- -- --

24 PM4 935 -- -- -- -- -- -- -- --

24 PM2.5 1467 -- -- -- -- -- -- -- --

24 PM2.5 1411 3 J -- -- -- -- -- -- --

24 PM2.5 1486 -- -- -- -- -- -- -- --

24 PM2.5 1479 -- -- -- -- -- -- -- --

25 PM100 1454 -- -- -- -- -- 3 J -- --

25 PM100 1437 -- -- -- -- -- -- -- --

25 PM100 1457 -- -- -- -- -- -- -- --

25 PM100 1451 -- -- -- -- -- -- -- --

25 PM10 1456 R R R R R R R R

25 PM10 1451 R R R R R R R R

25 PM10 1453 R R R R R R R R

25 PM10 1458 R R R R R R R R

25 PM10 1447 R R R R R R R R

25 PM10 1454 R R R R R R R R

25 PM4 913 -- -- -- -- -- 4 J

25 PM4 909 -- -- -- -- -- -- -- --

25 PM4 917 -- -- -- -- -- -- -- --

25 PM4 967 -- -- -- -- -- -- -- --

25 PM2.5 1431 -- -- -- -- -- 3 J -- --
124

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

25 PM2.5 1414 -- -- -- -- -- -- -- --

25 PM2.5 1433 -- -- -- -- -- -- -- --

25 PM2.5 1444 -- -- -- -- -- -- -- --

26 PM100 1447 -- -- -- -- -- -- -- --

26 PM100 1445 7 J -- -- -- -- -- -- --

26 PM100 1424 -- -- -- -- -- -- -- --

26 PM100 1432 -- -- -- -- -- -- -- --

26 PM10 1453 -- -- -- -- -- -- -- --

26 PM10 1462 R R R R R R R R

26 PM10 1469 -- -- -- -- -- -- -- --

26 PM10 1445 -- -- -- -- -- -- -- --

26 PM10 1429 R R R R R R R R

26 PM10 1424 R R R R R R R R

26 PM4 894 -- -- -- -- -- -- -- --

26 PM4 909 -- -- -- -- -- -- -- --

26 PM4 889 -- -- -- -- -- -- -- --

26 PM4 886 -- -- -- -- -- -- -- --

26 PM2.5 1449 -- -- -- -- -- -- -- --

26 PM2.5 1444 -- -- -- -- -- -- -- --

26 PM2.5 1436 -- -- -- -- -- -- -- --

26 PM2.5 1429 -- -- -- -- -- -- -- --

27 PM100 1473 -- -- -- -- -- -- -- --

27 PM100 1450 3 J -- -- -- -- -- -- --

27 PM100 1469 -- -- -- -- -- -- -- --

27 PM100 1454 -- -- -- -- -- -- -- --

27 PM10 1467 -- -- -- -- -- -- -- --

27 PM10 1457 -- -- -- -- -- -- -- --

27 PM10 1434 -- -- -- -- -- -- -- --

27 PM10 1435 -- -- -- -- -- -- -- --

27 PM4 923 -- -- -- -- -- -- -- --

27 PM4 902 -- -- -- -- -- -- -- --

27 PM4 917 -- -- -- -- -- -- -- --

27 PM4 906 -- -- -- -- -- -- -- --

27 PM4 902 -- -- -- -- -- -- -- --

27 PM2.5 1462 -- -- -- -- -- -- -- --

27 PM2.5 1457 -- -- -- -- -- -- -- --

27 PM2.5 1458 -- -- -- -- -- -- -- --

27 PM2.5 1451 -- -- -- -- -- -- -- --

28 PM100 1427 -- -- -- -- -- 3 J -- --
125

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

28 PM100 1458 -- -- -- -- -- -- -- --

28 PM100 1468 3 J -- -- -- -- -- -- 4 J

28 PM100 1380 -- -- -- -- -- -- -- --

28 PM100 1346 -- -- -- -- -- -- -- --

28 PM100 1337 -- -- -- -- -- -- -- --

28 PM10 1400 -- -- -- -- -- 3 J -- --

28 PM10 1450 -- -- -- -- -- -- -- --

28 PM10 1366 -- -- -- -- -- 3 J -- --

28 PM10 1343 -- -- -- -- -- -- -- --

28 PM4 898 -- -- -- -- -- 5 J -- --

28 PM4 891 -- -- -- -- -- -- -- --

28 PM4 859 -- -- -- -- -- 5 J -- --

28 PM4 810 -- -- -- -- -- -- -- --

28 PM2.5 1396 -- -- -- -- -- -- -- --

28 PM2.5 1371 -- -- -- -- -- -- -- --

28 PM2.5 1319 -- -- -- -- -- -- -- --

28 PM2.5 1451 -- -- -- -- -- -- -- --

29 PM100 1519 -- -- -- -- -- -- -- --

29 PM100 1468 4 J -- -- -- -- -- -- --

29 PM100 1447 -- -- -- -- -- -- -- --

29 PM10 1527 -- -- -- -- -- -- -- --

29 PM10 1481 -- -- -- -- -- -- -- --

29 PM10 1447 -- -- -- -- -- -- -- --

29 PM10 1212 -- -- -- -- -- 3 J -- --

29 PM4 927 12 J -- -- -- -- -- -- --

29 PM4 897 19 J -- -- -- -- -- -- --

29 PM4 887 -- -- -- -- -- 5 J -- --

29 PM4 746 -- -- -- -- -- 5 J -- --

29 PM2.5 1451 -- -- -- -- -- -- -- --

30 PM10 1307 3 J -- -- -- -- 3 J -- --

30 PM10 1297 -- -- -- -- -- -- -- --

30 PM4 822 -- -- -- -- -- 5 J -- --

30 PM4 781 -- -- -- -- -- -- -- --

30 PM2.5 1307 -- -- -- -- -- -- -- --

Results for Individual Comparison Buildings Sampled Above 59th Street (Buildings 31–34)

31 PM10 1346 -- -- -- -- -- -- -- --

31 PM10 1328 -- -- -- -- -- 3 J -- --

31 PM10 1347 -- -- -- -- -- -- -- --

31 PM10 1324 -- -- -- -- -- -- -- --
126

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

31 PM10 1371 -- -- -- -- -- -- -- --

31 PM10 1401 -- -- -- -- -- 3 J -- --

31 PM4 828 -- -- -- -- -- -- -- --

31 PM4 819 -- -- -- -- -- -- -- --

31 PM4 852 -- -- -- -- -- -- -- --

31 PM4 867 -- -- -- -- -- 5 J -- --

32 PM100 1318 -- -- -- -- -- 3 J -- --

32 PM100 1336 -- -- -- -- -- -- -- --

32 PM100 1351 -- -- -- -- -- -- -- --

32 PM100 1316 -- -- -- -- -- -- -- --

32 PM10 1312 -- -- -- -- -- 3 J -- --

32 PM10 1337 -- -- -- -- -- -- -- --

32 PM10 1317 -- -- -- -- -- -- -- --

32 PM10 1312 -- -- -- -- -- -- -- --

32 PM4 808 -- -- -- -- -- 5 J -- --

32 PM4 805 -- -- -- -- -- 5 J -- --

32 PM4 776 -- -- -- -- -- -- -- --

32 PM4 828 -- -- -- -- -- -- -- --

32 PM4 826 -- -- -- -- -- -- -- --

32 PM2.5 1311 -- -- -- -- -- 3 J -- --

32 PM2.5 1418 -- -- -- -- -- -- -- --

32 PM2.5 1315 -- -- -- -- -- -- -- --

33 PM100 1338 -- -- -- -- -- -- -- --

33 PM10 1338 -- -- -- -- -- -- -- --

33 PM4 831 -- -- -- -- -- -- -- --

33 PM4 838 -- -- -- -- -- -- -- --

33 PM2.5 1338 -- -- -- -- -- -- -- --

34 PM100 1307 -- -- -- -- -- -- -- --

34 PM100 1315 -- -- -- -- -- -- -- --

34 PM100 1309 -- -- -- -- -- -- -- --

34 PM100 1232 -- -- -- -- -- -- -- --

34 PM10 1318 R R R R R R R R

34 PM10 1327 -- -- -- -- -- -- -- --

34 PM10 1238 -- -- -- -- -- -- -- --

34 PM4 816 -- -- -- -- -- -- -- --

34 PM4 848 -- -- -- -- -- -- -- --

34 PM4 830 -- -- -- -- -- -- -- --

34 PM4 782 -- -- -- -- -- -- -- --

34 PM4 770 -- -- -- -- -- -- -- --
127

Building 

Number

Particle Size 

Fraction

Sample 

Volume 

(L)

Quartz

(μg/m3)

Cristobalite

(μg/m3)

Tridymite

(μg/m3)

Calcite

μg/m3)

Portlandite 

(μg/m3)

Gypsum

(μg/m3)

Mica

μg/m3)

Halite

(μg/m3))

34 PM2.5 1308 -- -- -- -- -- -- -- --

34 PM2.5 1348 -- -- -- -- -- -- -- --

34 PM2.5 1223 -- -- -- -- -- -- -- --

--: Not detected. Mineral was not detected above the analytical sensitivity in the associated sample.

Detect: Mineral was detected above the analytical sensitivity for the associated sample.

J: Result presented is an estimate. Due to inconsistencies during sample collection/analysis, the result is only 

an estimate of the actual value. The actual value could be higher or lower than the value shown.

ND: Not detected. Mineral was not detected above the analytical sensitivity in the associated sample.

NS: Not sampled. The associated method was not used at any of the measured locations in the building.

R: Result was rejected. Due to inconsistencies during sample collection/analysis, the result values for the 

sample were rejected.

μg/m3: microgram per cubic meter of air.