NYC-WTC_000199742

NYC 9/11 Public Portal Document

[ Jessica Leighton - RA_sitrep12-27.wpd

above the detection limit (ranging from 20 ppbv to 50 ppbv).

Direct Reading Instruments

NYC/ER (Dec 19)

o Nothing of significance reported with routine daily monitoring parameters. o Monitoring conducted for hexamethylene diisocyanate (HDI), methylene bis(4-phenyl isocyanate) (MDI), and toluene-2,4-diisocyanate (TDI). o Locations monitored for the cyanide compounds included: North Tower, South Tower, Vista Hotel, Building No. 4, and Locations A, B, C, D, E, P, R, S, 3B from the fixed ambient air sampling stations. o Measurements for the cyanide compounds consisted of one to three 3-minute run(s) taken once that day at each of the locations. o Low levels of HDI, MDI, and/or TDI identified at the North Tower, South Tower, Vista Hotel, and Location B (Note: not all compounds were identified at each of the locations). o The MDI and TDI hits were all measured at or below the detection limit (2 ppb). o As a point of comparison, all levels detected were below the respective OSHA PELs and NIOSH RELs for these compounds. The NIOSH REL for HDI and MDI is 0.005 ppm. The OSHA PEL for TDI is 0.02 ppm. o Note: The cassettes used to monitor for these cyanide compounds also respond positively to elevated levels of chlorine, nitrogen dioxide, nitric oxide, and ozone. o Note: Air samples (15-minute grabs) were collected for fixed laboratory analysis at two of the work-zone locations and at each of the fixed ambient air sampling stations. Results are pending.

NYC / ER (Dec 20)

o Nothing of significance reported.

NYC/ER (Dec 21)

o Nothing of significance reported.

NYC / ER (Dec 22)

o Nothing of significance reported.

NYC / ER (Dec 23)

o Nothing of significance reported.

CITY_21MC100_002458795

NYC-WTC_000199747