NYC-WTC_000195194

NYC 9/11 Public Portal Document

dioxin. The concentrations of dioxin were similar to the pre-cleaning samples. The TEQ concentration for each sample was below the criterion of 4 ng/m^

Post Cleaning Samples (Test 4E) - Three wipe samples were collected and analyzed for dioxin. The concentrations of dioxin were slightly lower than the pre-cleaning samples. The TEQ concentration for each sample was below the criterion of 4 ng/m’.

Gypsum Before Cleaning Samples - Pre-cleaning air samples were not collected

Post P' Cleaning Samples (Test 4A) - Two air samples were collected. Gypsum was not detected in the air samples above the detection limit range of 0.008 mg/m^ to 0.017 mg/m^.

Post P‘ Cleaning Samples (Test 4B) - Two air samples were collected. Gypsum was detected in air at concentrations of 0.011 mg/m^ and 0.014 mg/m’.

Post P' Cleaning Samples (Test 4C) - Two air samples were collected. Gypsum was detected in air above the detection limit with the results of 0.009 mg/m’ to 0.012 mg/m\

Le^ Before Cleaning Samples - Four micro vacuum samples and four wipe samples were collected. Lead was detected in all of the micro vacuum samples and wipe samples. Three of the four micro vacuum results exceeded the comparison value of 25 pg/ft^, ranging from 28.2 pg/ft^ tol81 pg/ft^. Wipe sample concentrations exceeded the primary clearance criterion of 25 pg/ft^ in all of the samples, ranging in concentrations from 74.7 pg/ft^ to 433 pg/ft^

Post P' Cleaning Samples (Test 4A) - Two air samples, four micro vacuum samples, and four wipe samples were collected after the first cleaning. The two air samples were below the primary clearance criterion of 1.0 pg/m^. The results of the micro vacuum and wipe samples show that, while all of the micro vacuum and two of the wipes samples were below the comparison value or primary clearance criterion. The remaining two wipe samples exceeded the primary clearance criterion with concentrations of 64.5 pg/ft^ and 146 pg/ft2.

Post P' Cleaning Samples (Test 4B) - Two air samples and four wipe samples were collected. The two air samples were below the primary clearance criterion of 1.0 pg/m\ Two of the four wipe samples exceeded the primary clearance criterion at concentrations of 147 pg/ft2 and 556 pg/ft^.

Post P' Cleaning Samples (Test 4C) - Two air samples and four micro vacuum samples were collected. The two air samples both exceeded the primary clearance criterion at 1.89 pg/m^ and 2.56 pg/m\ All four micro vacuum samples were below the comparison value of 25 pgriV’,

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