NYC-WTC_000218573

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan February 14, 2002 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 3:30 P.M. The results are described below:

Temperature

Indoor dry bulb temperature measurements ranged from 67.3°F to 74.1°F (A.M.) and 67.6°F to 77.8°F'(PM). In the morning, two (2) of the measurements were below 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, three (3) measurements were below and two (2) measurements were above the recommended range. The average outdoor temperature was 44.2°F (A.M.) and 38.5°F (P.M.).

Relative Humidity

The relative humidity indoors ranged from 16.8 to 23.1 percent (A.M.) and 11.0 to 13.5 percent (P.M.). All measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity averaged 24.9 percent (A.M.) and 14.5 percent (P.M.).

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 490 to 948 ppm (A.M.) and 460 to 670 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) CO2 concentrations averaged 489 ppm (A.M.) and 453 ppm (P.M.). Therefore, the maximum acceptable level of CO2 at this location was 1189 ppm (background level -t- 700 ppm). The highest indoor level was measured in Classroom 506. 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 CO2 indoors is occupant respiration. The 2nd and 3’'d floors of the school building were not occupied during ATC’s assessment.

Carbon Monoxide Concentration

Carbon monoxide was not detected indoors (0 ppm). The outdoor CO concentration was 1 to 2 ppm (A.M.) and 0 ppm (P.M.).

Respirable Particulates (PM2,s)

Respirable particulate concentrations* indoors ranged from 9 pg/m^ to 18 pg/m^ (A.M.) and 4 pg/m3 to 12 pg/m3 (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 14 pg/m^ (A.M.) and 9 pg/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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