NYC-WTC_000209133

NYC 9/11 Public Portal Document

02/12/2002 12:47 FAX 212 353 8306 ATC ®004/015

February 12, 2002 I I Mr. Bernard P. Orlan Indoor Air Quality Assessment Page 3 P. S. 89M ATC Project No. 15-19125-0297

Real-Time Environmental Measurements ) ATC collected eighty (80) sets of real-time environmental measurements consisting of eight (8) outdoors and thirty-two (32) inside in the morning (A.M.) and the same number of readings in the afternoon (P,M.). All five floors of the school were surveyed. The field data sheets are found in the Attachment, Readings began at 8;00 A.M. and concluded after 1:55 P.M. The results are described below:

Temperature

Indoor dry bulb temperature measurements ranged from 68.3°F to 73.9°F (A.M.) and 68-2°F to 77.7’? (PM). In the morning, all of the measurements were within the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). In the afternoon, only one (1) measurement was above the recommended range. The average outdoor temperature was 53.1 °F (A.M.) and 37,9’? (P.M.).

Relative Humidity

The relative humidity indoors ranged from 24.0 to 32.0 percent (A.M.) and 16.0 to 29.8 percent (P.M.). Three (3) measurements collected in the morning were within the recommended range. All other measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity averaged 24.7 percent (A.M-) and 22.7 percent (P.M.).

Carbon Dioxide Concentr-ation

Carbon dioxide concentrations indoors ranged from 460 to 1084 ppm (A.M.) and 460 to 996 ppm (P-M.). All CO2 measurements collected were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO? concentrations averaged 489 ppm (A.M.) and 464 ppm (P.M-). Therefore, the maximum acceptable level of COy at this location was 1189 ppm (background level + 700 ppm). The highest indoor level was measured in Classroom 408. Levels above the recommended maximum do not indicate a health risk. Carbon dioxide measurements are used as an indicator of available outdoor air. The primary source of CO? indoors is occupant respiration. The 2nd and 3rd floors of the school building were not occupied during ATC’s assessment.

Carbon Monoxide Conoentration

Carbon monoxide was not detected indoors (0 ppm). The outdoor CO concentration was 1 ppm (A-M.) and 0 ppm (P.M.).

Respirable Particulates (PM2 5)

Respirable particulate concentrations* indoors ranged from 3 to 9 pg/m^ (A.M.) and 3 pg/m^ to 9 pg/m^ (P.M.). All indoor measurements were below the NPAAQS of 65 pg/m^ (24- hour average). The average PM2,5 concentration* for the entire school building was approximately 5 pg/m^ (A.M.) and 6 gg/m^ (P.M.). None of the indoor measurements were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals such as

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