### Final Technical Report of th e 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 Heal th and Human Services

As a part of the



### World Trade Center Environme ntal Assessment Working Group

# September 11, 2001

In rememb r ance of those w h o w e r e lost on September 11, 2001, and to the families and friends w h o w ill love th em for e ver and keep th eir m e mor i es aliv e.

In grateful recognition of th e countless responders and the many w h o supported their effor t s.

Ne w York City Department of He alth and Mental Hyg i e n e

U.S. Agenc y for Toxic Substances and Disease RegistryEXE CUTI V E SUMM ARY

From Nove mber 4 thro ugh Decem ber 11, 2001, environm ental sam p les were collected in and around 30 residen t ial buildings in lower Manhattan. In addition, f our buildings above 59th Street were sam p led and used as a co m p arison area for this investigation. The New York City Departm e nt of Health and Me ntal Hygiene (NYC DOHMH) and the U.S. Agency for Toxic Substances and D i sease Registry (ATSDR) conducted this lim ited investigation with support and collaboration from the U. S. Public Hea lth Service Comm issioned Corps Readiness Forc e and the World Trad e Center Env i ro nm ental Assessm ent Working Group. The purpose of the sam p ling was to assess the com position of both outdoor and indoor set tled surface and airborne dus t within residential areas around the World Trade Center. This inform a tion was used to help determ ine whether additional p ublic health action s are n eeded to address any remaining W o rld Trade Centerrela ted dus t inside res i de ntia l are a s. The in form a tion collected could also be used to

com p are the findings from the locations that were known or were likely to have received dust dir e ctly f r om the collaps e of the W o rld Trade Center towe rs, to findings from areas that were unlikely to have received dust di rectly from the disaster (com parison areas).

Attention was given to those m a terials reasona bly expected to be in the original dust cloud and in dust generated by ongoing activitie s at the W o rld Trade Center. The focus was on building m a terials that have been show n to have irritant properties (e.g., synthetic vitreous fibers [SVF] and gypsum ) a nd be associ ated with long-term health concerns (i.e., crystalline s i lica and asb e stos). The s a m p le s collected during this investigation were analyzed for the following m a terials: asbe stos, SV F, m i neral com ponents of concrete (crystalline silica, ca lcite, and portlandite), and m i neral components of building wallboard (gypsum , m i ca , and halite). Efforts were m a de to get as m u ch infor m ation as possible with the sam p ling that could be conducted, given accessibility and equipm e n t lim itations.

Results fro m this inves t igation do n o t necess a rily reflect con d itions that would be found in other buildings, at other tim e s just follo wing the collapse, or after the sam p ling period. The m easurem ents reflect conditions presen t at the tim e of the sam p ling (Nove m b er 4– Decem ber 12, 2001) in the build ings and area s sampled. The lim ited num b er of results obtained from the com p arison areas above 59th Street was an attem p t to determ ine the New York City–specific bac kground levels of asbestos, SVF, m i neral components of concrete (quartz, calcite, and portlandite), and m i neral com ponents of building wallboard (gypsum , m i ca, and halite).

Sampling Overview

U.S. Public Health Service Commissioned Corp s Readiness F o rce Officers were detailed to the New York City Departm e nt of Hea lth and Mental Hygiene and composed the

sam p ling team s for this investig ation

. The team s com p leted a survey form for each

sam p ling location. The infor m ation collected by the survey w a s obtained from direct

1observations and from owners or representati ves of building m a nage m e nt when available. The survey form and photographs were review ed along with the analytical results to put the sam p ling results in to the contex t of wher e and how the sam p les were obtained and to determ ine th e genera l co nditions of the sam p ling locations.

Air and settled surface d u st sam p les were collected and analy zed for the following

m a terials used in W T C construction com pone nts: asbestos, S V F, crystalline silica, calcite, portlandite, gypsum

, m i ca, and halite. S V F ( e.g., fiberglass) is used in thousands of products because of its chem ical resistan ce, strength, and ability to insu late against heat and sound. All of the cr ystalline m i nerals analyzed in this project are commonly used in building construction m a terials. Quartz, a for m of crystalline silica , is a na tur a lly occurring mineral and is a com ponent of cem ent. Cristobalite and trid ymite are different crysta lline f o rm s of silic a. Calcite and portlandite are naturally occurring, high pH

m i nerals used in cem ents and m o rtars. Gypsum is a naturally occurring m i neral used in plaster, wallboard, and in som e ce ments. Mi ca is a group of naturally occurring m i nerals that are used in paint, joint cem ents, plastics, roofing, and rubber. Halite (also known as rock salt or sodium chloride) is used in ceram ic glazes, fire extinguish ing

, m e tallu rgy, and highway de-icing and table salt.

In addition to analyzing the sam p les for the fibers and m i nerals found in comm on building m a teria l s, when a su fficient quantity of settled su rf ac e dust was p r esent, it wa s

m i xed with water and the pH of th e resulting m i xture was m easured.

Air Samples

Air sam p les were collected using vacuum pum p s to draw air through a filter positioned at an adult’s br eathing leve l. In add itio n to a f ilter f o r f i ber ana l ysis, m u ltiple particulate

sam p lers were placed at each sam p ling locat ion to collect different p a rticle sizes including respirable (P M4 and PM2.5), thorac ic (PM10), and total inhalable (PM100). This resulted in the collecti on of overlapping, or neste d, particulate size fractions.

The particle size determ ines how deeply a par tic le can travel into th e resp ira t ory trac t. Respirab le p a rticle s with diam eters o f 4 m i crons or less (PM4 ) are v e ry s m all partic le s that can be breathed in and can travel deep ly into the air sacs of the lung. At som e locations an other sam p ler was used that co lle cte d a sm aller s e t of respira b le par tic les, those with diam eters of 21⁄2 m i crons (PM2.5) or less. Another sam p ler collected particles with diam eters of 10 m i crons (PM10) or le ss. T h is sam p ler would collect not only respirable p a rticles, but also thos e slightly larg er particle s tha t tend to lan d in the upp er regions of the respiratory tract, including th e throa t . A f ourth sam p ler colle cted a large r set of particles, those 100 m i crons (P M100) or less in diam eter. The larger particles in this fraction can land in the nose and throat. W h er e a particle lands de te rmines what ty pes of health effects m i ght be experienced. Part icles too large to travel into th e narrower passages of the lower respiratory tract m i ght deposit in the upper airways (e.g., the nose and throat) and cause irritation. Sim ilarly, la rger particles m i ght cause eye irritation. If

2the settled s u rface dust contains sufficient am ounts of particles of a very s m all size, th en effects consistent with particles reach i ng the lower resp iratory tract m i ght occur (coughing, shortness of breath).

Each of the particulate air sam p le fractions wa s a n alyzed for crystalline m i nerals (qu a rtz, cristobalite, tridym ite, calcit e, portlandite, gypsum, m i ca, and halite). X-ray diffraction analys is (X RD) identif ies a m i neral by the uni que diffraction pattern given off when the
x-ray s t rik e s its su rface. The diffraction pattern serves as a “fingerprin t ” to identify the

m i neral present.

Other air sa mples were screen ed for fibers using phase contrast m i croscopy (PCM) to count the total num ber of all fibers present. If the concentration of to tal fibers was higher than the m a xim u m concentration of fibers found in the com p arison hom es (0.003 fibers per cubic centim eter of air) the sam p le wa s re-analyzed for asbestos by transm ission electron m i croscopy (TE M ). Additio nally, s canning electron m i croscopy (SEM) was used to look for SVF if t h e PCM fiber counts was higher than 0.003 fibers per cubic centim eter (f/cc) and if the settled su rface dus t s a mple from that area contained SVF.

Settled Surface Dust Samples

The com position of settled surface d u st reflec ts p a rticle s and fibers that h a ve been track ed into an area o r th at were p r es ent in the air and have with tim e, deposited on surfaces. Settled su rface dust was collected i ndoo rs using a sp ecialized v a cuum cleaner. Outside settled surface d u st was collected by s c o oping any visible dus t-ty pe m a terial into a container

. As with the air sam p les, the settled s u rface dust s a m p les were analyzed to assess the presence of fibers and m i nerals. The an alysis p e rform e d does not allow the determ ination of what size par tic les are pr esent in the dust. T h e com position of the se ttled surface dust was evaluated to determine if, on the basis of its com position, it could be an irritan t if it becam e airborne or came in contact with skin or eyes during clean i ng activ ities.

The dust samples were analyzed for the pres ence of asbestos and SVF using polarized light m i croscopy (PLM). PLM can distingu ish between fiber types by their unique appearance and color w h en viewed under diffe rent wavelengths of light. In addition, TEM analysis was conducted on all dust sam p les that showed asbestos content by P L M as less than 1%. TEM analysis is very specific, can detect s m aller fi bers of asbestos, and is subje c t to less in te rf er ence than P L M.

The dust samples were also analyzed for m i neral content using XRD as described previous ly f o r the a i r s a mples. For the dust sam p les, th e m i neral and th e f i ber re sults are expressed as a percent, indicat ing the weight percent each component represents in the portion of the dust sam p le analyzed. The di fferent analy tical techniques, XRD and

m i croscopy (PLM, TEM, SEM), help to characterize what was in the settled surface d u st; however the results from the two m e thods each p e rform e d on a portion of the dust

3collected, cannot sim p ly be added together to “sum up” what was in the dust. XRD results are based upon the weight of the dus t sam p le analyzed. W h ile, PLM, TEM, and SEM results are based on the surface area viewed under the m i croscope.

Limitations

W h ile the g o al of the sa mpling was to evalu a te the air and dust sam p les for a range of
contam inants, there is no one sam p le collecti on m e thod or analysis th at can provide all of the determ inations that w e re desired. Th e analys is stra tegy wa s to iden tif y what

com ponents were present in orde r to provide the public with in for m ation quickly if any of the analyses revealed a s i gnificant co ncern. In order to strive for both of those goals,

som e modifications to conventional protocol s were m a de whic h lim ited som e analyses from determining the precise level of the m a terials in the sample (e.g., X R D conducted on air and dust sam p les). W h enever an anal ysis is expanded beyond its specific intent, there is th e potential los s of sensitiv ity and an in creas e in th e variab ility in the data. Those particular analytic al resu lts are reported as estim ated values and m a rked with a “J.”

Results for the airborne particulate m a tter we re rejected due to issues found during the quality assurance analysis. However, the XRD analysis for airborne m i nerals that used the sam e f ilter sam p les a s the par t icu l ate m a tte r a n alysis are c onsidered v a lid bec a use the analys is m e thod does not depend on the filter sample weighin g process us ed to determine the particulate m a tter concentration. The XRD mineral air concentrations are based on individual mineral weight standard curves—not the weight of the dust sam p le collected on the f ilters

. These stan dard curv es are not im pacted by pr e- and post-s a mpling f ilte r weight variability.

Air Samplin g Results

Total fiber counts of air sam p les taken in lower Manhattan were sim ilar to the

com p arison areas above 59th Street sam p led during this investigation. The six lower Manhattan areas th at had elevated to tal fi ber counts were re-exam i ned by TEM and SEM to determ ine the types of fibers. The TEM and SEM results indicated that neither asbestos nor synthetic vitreous fibers (e.g., fiberglass) contri buted to the elevated total fiber counts.

Air sam p ling results for m i nerals detected quartz (a form of crystalline silica) and other building -re lated m a teria l s in lowe r Manhattan. The other form s of cr ystalline silic a were not detected in any air samples excep t for a one-tim e detection of cristobalite. The estim ated co ncentration s of these m i nerals in air were low. In som e locations, m i neral

com ponents of concrete (quartz, calcite, and portlandite) and m i neral components of building wallboard (gypsum

, m i ca, and halite ) w e re detected in air sam p les at higher estim ated le vels in lowe r Manhattan residen t ia l a r eas th an in sam p les taken at com p arison residential areas above 59th Street. T h e levels of m i nerals seen in airborne dust do not

4pose potential health hazards ev en for a continuous year of exposure at the highest levels detected.

Settled Surface Dust Results

Results of th e settled su rface dust ana l ysis indi c a te the com position of se ttled surface d u st in lower Manhattan is different than the dus t analyzed from the com p arison areas abov e 59th Street. Although the m a terial s f ound are consistent with m a terials expected from the World Trad e Center co llapse, thes e results canno t determ ine the actual so urce of the

m a terials present becaus e these m a terial s are common building com ponents and can

com e from other sources in a busy urban area.

In lower Manhattan, asbestos was found in i ndoor dust in 15 of 83 (18%) sam p les 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%) outdoo r sam p les at levels ranging from <1% to 3.4%. Indoo r settled surface dust con t ained SVF in 40 of 83 (48%) locations ranging from 2% to 35% of the dust content. SV F was de tected in 11 of 14 (79%) outdoor locations at levels ranging from 1% to 72%. No asbestos or SVF was detected in dust in the com p arison areas ab ove 59th Street.

The XRD analysis for crystalline m i nerals in se ttled surface d u st is s e m i quantitative (estim ated values, indicated by “J”). Howeve r, quartz, calcite, por tlandite and gypsum appear to make up a higher percentage of dust in som e buildings in lower Manhattan when com p ared to settled surface du st sam p le s from building s above 59th Street. Quartz was detected up to an estim ated 31%J vers us up to 2%J found in the com p arison areas above 59th Street. Neither cristo balite nor tridymite was dete cted in any of the settled surface dust sam p les. Sim ilarly gypsum was found at a m a ximum estim a t ed concentration of 30%J in sett led su rf ace dust, h i gh er than the 4 % J estim a ted in the

com p arison areas above 59th Stre et. Calcite and portlandite had m a xi m u m concentrations of 21%J and 8%J respectivel y. At lower Manhattan loca tions sam p led, quartz was detected in 81% of common areas and 53% of residences. Gypsum was seen in 88% of common areas and 79% of residences. Mine rals were found in all lower Manhattan outdoor settled surface d u st sam p les at estim at ed values ranging as high as 27%J quartz, 19%J calcite, 6%J portlandite, and 27%J gyps um. No visible settled outdoor dust w a s available in the com p arison areas ab ove 59th Street.

Several of th e m i nerals d e tected in th e set tled su rface dust s a mples, such as portlandite and calcite, can m a ke the dust m o re alkaline , or raise the pH. Only two dust sam p les provided enough m a terial for the determ ination of pH. The sa mples, collected from two outdoor locations in low e r Ma nhattan, had pH levels of 8.6 and 9.8. On the pH scale, values less than 7 are considered acidic, a va lue of 7 is neutral, and values above 7 are alkaline or basic. Based on the results of th e pH analyses, thes e dust sam p les are s ligh t ly alkaline. This is consistent with th e d e tec tion of portlandite an d calc ite (alkaline m i ner a ls present in concrete) in the m i neral analysis of the dust sa m p le from the sam e location.

5Conclusions

Based upon the analytical results of sam p les taken between Novem b er 4 through Decem ber 11, 2001, and inform ation collected du ring th e sampling effort, the New York City Departm e nt of Health and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease Registry m a ke th e following conclusions (not in order of im portance).

• Total fiber counts of air sam p les taken in lower Manhattan were sim ilar to the

com p arison areas above 59th Street sam p led during this investigation. The six lower Manhattan areas that had elevated total fiber counts were re-exam i ned by
transm ission electron m i croscopy (T EM) and scanning electron m i croscopy (SEM). The TEM and SEM results indicat ed that neither asbestos nor SV F contributed to the elevated fiber counts.

• Low levels of asbestos were found in som e settled surface dust, prim arily below Chambers Street. Many of the lo wer Manhattan locations sam p led had been prev io usly cleaned prior to th is i nvestigation. No asbestos was detected in the com p arison indoor dust sam p les taken north of 59th Street. 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 abatem en t. Following-up activity at the other locations did not find any asbe stos containing materials.

• W h en compared with the resu lts o b tained fro m the com p arison s a m p ling locations, th e lower Man h attan res i de ntia l are a s s a m p led by this inves tig a tion tended to have a greater percentage of SVF (pri marily fiberglass), m i neral

com ponents of concrete (quartz, calcite, and portlandite), and m i neral components of building wallboard (g ypsum , m i ca, and ha lite) in settled surface dust. However, the frequency of detections and prevalen ce pa tte r n s of these m i nerals are sim ilar in both residential areas.

• Exposure to significant am ounts of synt hetic vitreous fibers (SVF), m i neral

com ponents of concrete (quartz, calcite, and portlandite), and m i neral components of building wallboard (gypsum ) m a y 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 ar e associated with W o rld Trade Center r e la ted m a terials, these ef f ects will subs id e once expo sure to SVF, m i neral

com ponents of concrete, and m i neral com ponents of building wallboard end. Som e people with pre-existing heart or lung disease (e.g., asthm a ) or a previous history of very high levels of expos ures (occupational) to SVF, m i neral

com ponents of concrete, and m i neral com ponents m a y be more sensitive to the

6irritant effects of SVF, mineral com p onents of concrete, and m i neral components of building wallboard.

• Som e tim e s m i neral components of c oncrete (calcite and portlandite) and

m i neral components of building wallboa rd (gypsum , m i ca, and halite) w e re detec t ed in a i r sam p les at higher es tim a ted levels in lower M a nhattan res i dentia l areas than in sam p les taken at com p ar ison r e side ntia l are a s. These dete cted

m i neral levels are orders of m a gnitude below occ upational standards. Although the occupational standards do not account for sensitiv e ind i v i duals o r extended periods of exposure, they provide a com p arison to an established health guidance value. The levels of m i nerals seen in airborne dust do not pose potential health hazards even for a continuous year o f e xposure at the h i ghest levels detected.

• Som e settled surface d u st could b e co m e airborne if distu r b e d. Therefore, people could potentially inhale the as bestos, SV F, m i neral com ponents of

concre te (qu a rtz, calc i te, and portlandite), and m i nera l com ponents of building wallboard (gypsum

, m i ca , and halite) found in settled surf ace dust of som e lower Manhattan residences. Because we did not determine the weig ht of dust present in the areas sampled, it is not possible to de term ine whether an y pa rticula r residen ce had an elevated dust load ing. Appropriate continued frequent cleaning should

m i ni m i ze exposures.

• Several w o rst-case assum p tions were m a de in order to assess the potential longterm public health risks of airborne asbe stos and quartz. Som e of the assumptions were that no cleaning of indoor spaces ha s occurred or will occur, all fibers found in air were asbestos fibers, and the highest levels detec t ed la st f a ll in a i r r e present long-term air levels. Using these wors t-case assumptions, prolonged exposure (decades) to airborn e asb e stos and qu artz may increase the lon g -term , theo retical risk of people developing lung cancer and other adverse lung health effects (m ore than 1 additional case in 10,000 people e xposed). For indivi duals who conduct frequent cleaning of their residences, as r ecomm e nded in this report, or participate in the U.S. Environm ental Pro t ec tio n Ag ency cleaning/sam p ling program, it is unlikely that their exposure would rese m b le these worst-case conditions.

• A review of the building sam p ling result s f r om this inv e stig ation indica tes tha t there is not a consistent spatial distribution pattern of asbestos, SVF, m i neral

com ponents of concrete, and m i neral com ponents of wallboard in air and settled surface dust. This indicates that the m a terials are h e terog e neou sly dis t rib u ted. There are many factors that m a y contribu te to the heterogeneous distribution, including whether the area was cleane d (indoors and outdoors), cleaning m e thod, date since last cleaning, and how m u ch dust wa s initially in the ar ea. It is not clear which factors contributed to this pattern.

• Results from this inve stiga tion do not necess a rily reflect co nditions tha t would

78 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 resu lts obtained from the co mparison areas above 59th Street may or may not reflect the New York City-specific background levels of asbestos, SVF, mineral components of conc rete (quartz, calcite , and portlandite), and mineral components of building wa llboard (gypsum, mica, and halite).

Recommendations

Based upon the conclusions of this investiga tion, 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 vitr eous fibers (e.g., fiberglass), mineral components of concrete (quartz, calcite, and portlandite), and mineral components of building wallboard (gypsum, mica, a nd halite) were found in settled surface dust in lower Manhattan residential areas when compared to comparison residential areas, the New York City Depa rtment 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 freque nt cleaning is effective and to ensure that the health of the people of New Yo rk City is protected, the New York City Department of Health and Mental H ygiene 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, mi neral components of concrete (quartz, calcite, and portlandite), and mineral co mponents of building wallboard (gypsum, mica, and halite).

• Lower Manhattan residents concerne d 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.