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Comparison of Results of Aggressive vs Modified-Aggressive Testing Methods
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RESIDENTIAL DUST CLEANUP PROGRAM
(This Program Ended in 2003) |
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MESSAGE CENTER
TESTING RESULTS DATA SUPPLEMENTAL INFORMATION |
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Mold Information From NYC Department of Health & Mental
Hygiene: |
A comparison of results of aggressive versus modified aggressive testing methods indicates that the sampling protocol did impact the rate of apartments that were not cleared or where a result could not be determined. This was expected, as it was explained to residents, the aggressive test method is an extremely conservative method. A background level of 0.0002-0.0003 f/cc of asbestos in air is common in urban areas and a small percentage of ambient air samples would be expected to fail. The level of agitation associated with the aggressive sampling creates a greater potential for resuspension of dust. In addition, because EPA collected a larger than normal sample volume (3600 liters vs. 1200 liters a sample for AHERA) to attain the lower detection level, more dust and particles were pulled in and more filters became overloaded with particles. Because the modified aggressive method more aptly mimicked real-life activities, it was an appropriate method to use for testing homes in this program. A comparison of the two options of clean and test or test only using comparable sampling procedures showed very little difference in rates of homes cleared or not determined.
Asbestos Sampling Summary of Results
Results are categorized by clean and test and test-only sampling (please note, two apartments have undocumented sampling procedures and therefore were not included in the results listed in these tables). In addition, these two categories are further divided into aggressive or modified aggressive sampling. The percent of apartments and samples that were either not cleared or not determined is presented for each of the four aforementioned categories. Apartments that were not cleared had one or more samples that exceeded the health-based benchmark of 0.0009 f/cc. Apartments not determined had more than one sample that were unreadable by microscopy due to filter overload with particulate matter. In each case, re-cleaning was recommended.
Clean / Test Data and Modified-Aggressive Testing Results Summary by Quadrants
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Quadrant (Map)
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Nbr Apts
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Nbr Apts Not Determined
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Nbr Apts Not Cleared |
Nbr Samples
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Nbr Samples Overloads
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Nbr Samples Exceedances
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A
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843
|
67
|
9
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4924
|
72
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7
|
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B
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995
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27
|
6
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5426
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59
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15
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C
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723
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24
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5
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3602
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52
|
10
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D
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598
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9
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2
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3300
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14
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2
|
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Total
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3159
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127
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20
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17252
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197
|
34
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The majority of residents who signed up for the WTC Indoor Dust Cleanup Program opted for clean and test followed by modified aggressive sampling. 4.65% percent of these apartments were either not cleared or a result could not be determined after the first cleaning.
Test Only Data and Modified-Aggressive Testing Results Summary by Quadrants
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Quadrant (Map)
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Nbr Apts
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Nbr Apts Not Determined
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Nbr Apts Not Cleared |
Nbr Samples
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Nbr Samples Overloads
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Nbr Samples Exceedances
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A
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122
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12
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1
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767
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22
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1
|
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B
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189
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7
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5
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1089
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18
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16
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C
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137
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6
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2
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758
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11
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3
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D
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279
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6
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-
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1646
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27
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-
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Total
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727
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31
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8
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4260
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78
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20
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The test only followed by modified aggressive sampling apartments had a comparable not cleared/not determined rate (5.36%).
Clean / Test Data by Quadrants and Aggressive Testing Results Summary by Quadrants
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Quadrant (Map)
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Nbr Apts
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Nbr Apts Not Determined
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Nbr Apts Not Cleared |
Nbr Samples
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Nbr Samples Overloads
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Nbr Samples Exceedances
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A
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34
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-
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-
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185
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-
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-
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B
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19
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2
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2
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126
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2
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4
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C
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29
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3
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13
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220
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10
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43
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D
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158
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1
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-
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865
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2
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-
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Total
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240
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6
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15
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1396
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14
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47
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Similarly, clean and test apartments receiving aggressive sampling had a not cleared/not determined rate (8.75%) nearly identical to the test only apartments receiving aggressive sampling (8.82%), recieving a higher not cleared/not determined rate (8.75%) than the clean and test apartments receiving modified aggressive sampling (4.65%).
Test Only and Aggressive Testing Results Summary by Quadrants
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Quadrant (Map)
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Nbr Apts
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Nbr Apts Not Determined
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Nbr Apts Not Cleared |
Nbr Samples
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Nbr Samples Overloads
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Nbr Samples Exceedances
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A
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3
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1
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-
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18
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1
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-
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B
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-
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-
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-
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-
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-
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-
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C
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1
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1
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-
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6
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4
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-
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D
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30
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-
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-
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188
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-
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1
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Total
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34
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2
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1
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212
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5
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1
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Similarly, test only apartments receiving aggressive sampling had a higher not cleared/not determined rate (8.82%) than test only apartments receiving modified aggressive sampling (5.36%).
The same general trends were evident when only the percent of apartments not cleared were tallied - the rate of not cleared apartments was higher within both categories when aggressive (clean and test 6.2%, test only 2.9%) as opposed to modified aggressive (clean and test .63%, test only 1.1 %) sampling was performed.
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