NYC-WTC_000222470

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 16, 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 seventy (70) from inside the school building and ten (10) from outdoors. All five floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 8;00 A.M. and concluded at approximately 11:30 A.M.

Temperature

Indoor dry bulb temperature measurements ranged from 71.1 °F to 78.2 °F. Forty-eight (48) of the indoor measurements were above the range of 68 to 75°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 67.1 to 68.1 °F.

Relative Humidity

The relative humidity indoors ranged from 48.1 to 64.6 percent. All of the measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 57.1 to 63.0 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 515 ppm to 1290 ppm. One (1) of the CO2 measurements was above the ASHRAE Standard. 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 513 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1213 ppm (background level + 700 ppm). Levels above the recommended maximum do not indicate a health risk. Carbon dioxide measurements are used as an indicator of available outside makeup air. The primary source of CO2 indoors is occupant respiration. The school building was occupied during ATC’s assessment.

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Carbon monoxide concentrations indoors ranged from 2ppm to 3 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration was 2 ppm for all collected readings.

Respirable Particulates (PM2_5)

Respirable particulate concentrations* indoors ranged between 10 pg/m^ to 36pg/m3. All of the measurements were below the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. The average PM2,5 concentration for the entire school building was approximately 19 pg/m^. The PM2,5 average concentration was below the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration measurements ranged from 28 to 34 pg/m^ with an average of 31 pg/m^.

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