In Lower Manhattan buildings, whether occupied or not, the potential for problems is not over just because more than six months have elapsed since 9/11.
Construction—and destruction—of buildings around Ground Zero continues to release contaminants into the air that can be drawn into buildings through air handlers, open doors, and windows. Few, if any, buildings have been thoroughly cleaned. There is a real possibility that renovation or cleaning activities inside these structures will contaminate other unsuspecting tenant areas in the building.
We know this situation occurred, because we have found instances where the dust levels in occupied spaces have actually increased, months after 9/11, even though the air handlers were closed to outside air. We have also found asbestos contaminated air handlers (even downstream of the filters) in systems that had previously been thoroughly cleaned, indicating an internal source of re-contamination. We have even heard from dependable sources that boxes of business materials from contaminated buildings were moved elsewhere and cleaned—or used to get back in business, and predictably contaminated those spaces as well!
We know these things are true because we have performed dozens of air quality inspections in the Ground Zero area and have overseen many clean-ups.
There is no single simple solution to the issues of air quality in building spaces directly affected by the events of 9/11. A careful and tedious process of cleaning, demolition, rebuilding, and testing must be undertaken over the next several years to see that contamination and re-contamination do not subject the workers and residents of lower Manhattan to a future of exposure, anxiety and illness.
A Summary of Air Quality Testing in Surrounding Buildings
Atlantic Environmental, Inc. performed about 30 separate Air Quality surveys in buildings around Ground Zero after September 11, 2001. The first survey was on September 13, 2001 and we still are performing occasional surveys of buildings in the area. The proximity to Ground Zero was as close as across the street to about 5 blocks away. We also oversaw about 10 clean-ups of the spaces where there was contamination. The surveys were of both business and residential spaces where we represented mostly tenants, but some building owners and insurance companies. We did also test several vehicles that were within 5 blocks of Ground Zero. We performed a wide variety of tests depending on the client’s requests or requirements, and our recommendations.
The following is a list of the analysis performed noting that each location was different and some were only for 1 analyte:
* Concrete dust
* Calcium chloride
* Heavy metal – all
* Volatile Organic Compounds – scan
* Total dust
* Molds and bacteria
* Water tests for drinking water criteria, metals, and chemicals.
Although we found trace amounts of metals and some chemicals, they were also well within the most stringent guidelines for airborne materials. We suspect that these materials may also have been there in comparable amounts before September 11, 2001 but have no way of confirming such information.
The only agents that were above what we felt were safe/acceptable was asbestos and total dust. Total dust was a problem because in several instances it had settled in open or broken windows, doors/window sills, entranceways and inside air handlers. The high alkaline of the pulverized concrete dust made it very irritating to eyes and upper respiratory systems.
Perhaps it was something of a blessing that as the buildings at Ground Zero collapsed, the power went off preventing the air handlers from drawing in the clouds of dust and chemicals that emanated from the site.
The agent of real concern was asbestos. What we found presented us with several dilemmas in the first day or two of our tests. The standard air tests for asbestos by optical microscopy (specifically Phase Contrast Microscopy) showed no detectable asbestos. However, we immediately recognized that the information was valueless. Our analysis of bulk samples of the dust showed either very small thin fibers or no fibers at all but still appreciable amounts of asbestos in the samples. Some were over the 1% by weight quantity, which officially defined the samples as “asbestos-containing” by EPA, OSHA, and NYC DEP. It appears that the collapse of the towers created such powerful forces that finely pulverized the asbestos to very small fibers or non-fibrous particles.
There was a further problem, in that; the use of the alternate air sampling method of transmission electron microscopy (TEM) could only reflect what was presently in the air at the time of the test. This also was of little value since most of our testing was of buildings and spaces that were vacant, and even with limited (or no) operation of the air handling systems. The conditions containing did not reflect normal occupancy and did not address activity that would intentionally or unintentionally disturb any asbestos in the occupied spaces, or air handling systems.
We arrived at the obvious conclusion to test for asbestos in dust or asbestos in bulk settled material as a way to predict whether future activities in a currently vacant space would pose a significant health risk to occupant. We also applied the same criteria to occupied spaces, i.e., inspecting and testing for asbestos in settled dust in both occupied spaces and air handlers.
The only available method for sampling for asbestos in settled dust is a method established by ASTM (ASTMD-6480-99- Standard Test Method for Wipe Sampling Surfaces, Indirect Preparation and Analysis for Asbestos Structures Number Concentration by Transmission Electron Microscopy –March, 2000).
Another problem is settled dust in porous surfaces such as carpet. We became aware in the first clean up we oversaw that dry vacuuming of carpets was not adequately effective (this was confirmed by a study by EPA). Likewise, wipe tests were not effective in sampling imbedded particles. ASTM identified a microvac test method (ASTM D-5755-95) that we used for sampling carpets and other porous surfaces (chairs, drapes, etc.). No standards exist for what is safe/unsafe, acceptable/unacceptable for asbestos structures on surfaces. Further, no other professional or regulatory agency has published any information that we felt was credible.
We identified some criteria in the ASTM STP 1342 Course Manual that states:
Guidance Level of Surface Contamination (Asbestos)
Less than 1000 s/cm2 = No Contamination
1000 to 10,000 s/cm2 = Low Contamination
10,000 to 100,000 s/cm2 = Moderate Contamination
Over 100,000 s/cm2 = High Contamination
s/cm2 = asbestos structures per square centimeter of surface area sampled. We used the 100,000 s/cm2 as our criteria for acceptability unless our client wanted lower level of cleanliness.
At least at this point, we have found no instances where an asbestos surface concentration below 100,000 s/cm2 has resulted in an airborne concentration of asbestos above the EPA background level of 70 structures/mm2 or 0.01 fibers/cc by TEM analysis.
We recognize that the 100,000 s/mm2 is not an absolute cut off of acceptability. This was not a particular problem to us since wipe tests or vacuum tests tended to be low (less than 50,000) or high (300,000 to several million).
Building occupants continued to have a number of real dilemmas that they must confront. One of the greatest is the nature of buildings in the Ground Zero and their air handling systems. We have found at least one building where the asbestos content of settled dust IN THE AIR HANDLER – AFTER THE FILTERS WAS GREATER THAN 100,00 s/cm2 and greater than 1% asbestos.
Another dilemma was that in none of the buildings that we tested, were the air handlers providing service to just one tenant. The most significant problem was when the air handlers services more than 1 floor. This would present the potential for contamination of one floor or one tenant space by activities in another area of the building. These activities could, and did, include removing of furniture, partitions and fixtures. It also included work above false ceilings that acted as return air plenums, work on the ductwork/air handlers themselves and cleaning of files, papers, and storage containers in other occupied or unoccupied spaces.
All of these factors result in very high anxiety to occupants of buildings in the Ground Zero area. Even at its highest concentration, the asbestos structures are invisible. Many buildings are still under repair or are being renovated to make attractive space for new tenants where former tenants will not return. Construction dust, added to residual concrete dust from the collapse which is very irritating (at least in part due to its alkalinity) adds a significant psychological factor to this physical problem.
As of the writing of this paper, most identifiable problems of air quality inside building due to the events of 9/11 have been resolved – but not all. Further, the long-term effects of the exposures to asbestos or small amounts of many other physical agents has yet to be determined.