NYC-WTC_000219378

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 9, 2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance (M833)________ ATC Project No. 15-19125-0291 Real-Time Environmental Measurements

ATC collected one hundred (100) sets of real-time environmental measurements consisting of eighty-eight (88) in the school building and twelve (12) outdoors. Field data sheets are found in the Attachment. Readings began at 11:23 A.M. and concluded after 6:02 P.M. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 66.7 °F to 77.2 °F. Six (6) of the indoor measurements for temperature were below, eleven (11) measurements were above, and seventy- one (71) 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). The outdoor temperature ranged from 60.8 to 64.4 °F.

Relative Humidity

The relative humidity indoors ranged from 26.8 percent to 50.4 percent. Six (6) of the indoor measurements for relative humidity were below and eighty-two (82) were within the ASHRAE recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 30.7 to 36.6 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 459 ppm to 1637 ppm. Five (5) of the indoor measurements for CO2 were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 421 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1121 ppm (background level + 700 ppm). The highest level was measured in the cafeteria at 11:47AM with 200 occupants. 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.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors were between 1 to 3 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration ranged from 2 ppm to 4 ppm.

Respirable Particulates (PM2^5)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 34 pg/m^ with an average 12 pg/m^- All of the indoor measurements were below the NPAAQS of 65 pg/m^ 24- hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter and the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration ranged from 33 pg/m^ to 93 pg/m^ with an average of 59 pg/m^. Three (3) of the outdoor measurements was above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in

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NYC-WTC_000219380