NYC-WTC_000219394

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 25, 2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance fM833) ATC Project No. 15-19125-0291

Real-Tbme Environmental Measurements

ATC collected one hundred (100) sets of real-time environmental measurements consisting of eighty-eight (88) inside the school building and twelve (12) outdoors. Field data sheets are found in the Attachment. Readings were collected between 12:00 PM to 3:00 PM. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 68 °F to 68.9 °F. All of the measurements were below the range of 73 to 79°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 68 °F to 68.9 °F .

Relative Humidity

The relative humidity indoors ranged from 33 percent to 33.9 percent. All of the indoor measurements for relative humidity were within the ASHRAE recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 33 to 33.6 percent.

Carbon Dioxide Cmcentratipn

Carbon dioxide concentrations indoors ranged from 621 ppm to 691 ppm. All of the indoor measurements for CO2 were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 672 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1372 ppm (background level -1- 700 ppm). 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 were 0 ppm. These concentrations were below the NPAAQS/ASHRAlE guideline of 9 ppm. The outdoor CO concentrations were 0 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 2 pg/m^ to 4 pg/m^ with an average 3 pg/m^- All of the indoor and outdoor measurements for respirable particulates 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/m3 for sensitive individuals and children. The outdoor respirable particulate concentration ranged from 1 pg/m^ to 4 pg/m^ with an average of 3 pg/m^.

* The measurements made during this assessment were instantaneous readings, the NPAAQS is a 24-hour average.

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NYC-WTC_000219396