World Trade Center Asbestos

EPA collected wipe samples in a subset of the households that were cleaned and tested or tested only through the program. The samples were used to evaluate the effectiveness of the techniques -- wet mopping, wet wiping and HEPA vacuuming -- that were used and recommended for cleaning indoor spaces impacted by the collapse of the World Trade Center. They also contributed additional data to the body of information about materials from the disaster and their impacts.

In May 2002, EPA launched a voluntary program to either clean and test or just test any home in Lower Manhattan for asbestos in the air. Ultimately, over 4,100 homes participated in the program. The Agency also collected wipe samples in a subset of the households that were cleaned and tested or tested only through the program.

The samples were used to evaluate the effectiveness of the three techniques (wet wiping, wet mopping and HEPA vacuuming) that were used and recommended for cleaning indoor spaces impacted by the collapse of the World Trade Center. They also contributed additional data to the body of information about materials from the disaster and their impacts.

Wipe samples, collected by wiping a piece of soft filter paper over a representative hard surface such as a floor, were analyzed for dioxin and 23 elements, including lead and mercury, and evaluated against health-based screening levels. In homes that underwent testing only, samples were taken before testing for asbestos in the air. For apartments in the test-only program, samples were collected before air sampling and are equivalent to a pre-cleaning sample.

The samples were taken in approximately 263 homes that were cleaned and tested or tested only. The data includes pre- and post-cleaning wipe samples from 222 homes; some data also exists for 41 additional apartments.

The testing found that most of the contaminants were either not detectable or present at levels below the EPA screening levels. It also confirmed that the cleaning techniques used in the program and recommended to residents following the collapse of the buildings were effective in meeting the health-based benchmarks. In some cases, homes may have to be cleaned more than once to achieve these levels.

Lead was the contaminant most commonly encountered. Of the 222 apartments tested before and after cleaning, 70 had lead levels before cleaning that exceeded EPA's benchmark of 25 micrograms per square foot (ug/ft2), adapted from the U.S. Department of Housing and Urban Development (HUD) screening level. The number of apartments that exceeded 25 ug/ft2 was reduced to 16 after cleaning. Residents living in these16 apartments were informed about their levels and advised to continue using the recommended cleaning methods. In addition, they were provided information about how to contact staff at EPA and the New York City Department of Health and Mental Hygiene.

Lead, which can cause serious learning disabilities and behavioral problems in children, is commonly found in the air, water, soil and indoor dust of the urban environment, and in people's diets; it is often present in older housing that may contain lead-based paint. According to HUD data, about five percent of the housing stock in the Northeast has lead levels above the 25 ug/ft2 benchmark. In buildings constructed before 1939, more than 10 percent exceed 25 ug/ft2. This factor makes it difficult to distinguish between lead from World Trade Center dust and other sources, especially in older buildings.

Lead in settled dust can be a significant source of lead in a child's environment, making it important for children under seven years old to have their blood lead levels tested. If children under seven were living in residences that exceeded the 25 ug/ft2 benchmark used in the Lower Manhattan cleaning and testing program, EPA urged the families to have the children's blood lead levels tested.

The wipe samples were analyzed for dioxins and 23 elements:

1. aluminum (Al)
2. antimony (Sb)
3. arsenic (As)
4. barium (Ba)
5. beryllium (Be)
6. cadmium (Cd)
7. calcium (Ca)
8. chromium (Cr)
9. cobalt (Co)
10. copper (Cu)
11. iron (Fe)
12. lead (Pb)
13. magnesium (Mn)
14. manganese (Mg)
15. mercury (Hg)
16. nickel (Ni)
17. potassium (K)
18. selenium (Se)
19. silver (Ag)
20. sodium (Na)
21. thallium (Ti)
22. vanadium (V)
23. zinc (Zn)

Detected levels were compared to benchmarks (or screening values) outlined in a document entitled "Selecting Contaminants of Potential Concern and Setting Health Based Benchmarks."

World Trade Center Asbestos