NYC-WTC_000195194

NYC 9/11 Public Portal Document

5.8 Air Disturbance

The asbestos air samples were collected using two types of air disturbance prior to sampling. Either an aggressive technique, using a leaf blower and oscillating fans to disturb the air, or a modified-aggressive technique, using only oscillating fans to disturb the air was used. In several instances both methods were used in the same apartment to evaluate if there was a difference in the analytical results. Both the aggressive and modified-aggressive techniques are expected to create air disturbance over an eight-hour sampling period that represents either a worst-case or high-end (respectively) air movement in an indoor environment, which would provide a conservative estimate of the airborne asbestos concentration.

ii I Table Comparison of Airborne Asbestos Samples Collected Using Modified-Aggressive and Aggressive Air Disturbance Methods’’ w

resave Air JMsiurbenee Aggressive Air fiisiurltattce liMi SamplelP | Result I Units 9094-A-2A-25 0.0004 S>5pycc 9094-A-2A-28 < 0.0005 S>5p/cc 2A 9O94-A-2A-2O 0.0004 s> 5m/cc 9094-A-2A-29 < 0,0005 S>5m/cc 9094-A-2A-27 0,0004 S> 5p/cc 9094-A-2 A-30 < 0,0005 S> 5p/cc iS 9094-A--3B-39 < 0,0005 S> 5p/cc 3B 9094-A-3B-40 < 0 0005 S> 5p/cc 9Q94-A-3B-41 <0.0005 S>5m?cc ■ar ;i:9094-A-3€^233 < 0,0005 S> 5p/cc 9O94A-3C-35 < 0.0005 S> 5p/cc 3C: 9094-A-3C-33 < 0.0005 S> 5n/cc 9O94-A-3C-36 <0,0005 S>5p/{y 9094-A-3C-34 < 0,0005 S> 5p/cc 9094-A-3C-37 < 0.0005 S> 5p/cc 3» 90Q4-A-3D-23 < 0.0005 S> 5p/cc 9e-94-A-3P-33 < 0.0005 S>5m/cC 9094-A-3D-24 <0.0005 S>5p/cc 9094-A-3D-34 <0.0005 S>5p/cc 9O94-A-5C-33 0.0016 $>5p/cc 9094-A-5C-32 < 0,004 S> Sp/cc 9O94-A-5C-34 0.0015 S>5p/cc 4

* Number Below Detection Limit 9/13 « Percent Below Detection Limit 69.2% 80.0%

Average 8.00045 0.00671

In apartments where both methods were used, the modified-aggressive technique was used first and air samples were collected. Several days later, the aggressive technique was used and additional air samples were collected with no cleaning events occurring between sampling events. w ^’Samples below the detection limit were assigned a value equal to the detection limit. Comparison of asbestos air samples that were collected using modified-aggressive and aggressive air disturbance. The samples collected using modified-aggressive air disturbance (i.e., box fans) were collected several days prior to the samples collected using aggressive air disturbance (i.e., leaf blower and box fans). The comparison does not show any trends, as the percentage of samples below the detection limit was higher for the aggressive air disturbance while the average asbestos concentration was nominally lower for the modified-aggressive air disturbance. 115

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NYC-WTC_000195311