NYC-WTC_000223580

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 8, 2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance (M833)________ ATC Project No. 15-19125-0291 Real-Time Envikoxmemal .Measikemenis

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 morning to evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 71.1 °F to 85.9 °F. Thirty-six (36) of the indoor measurements collected were below and two (2) indoor measurements were above 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 71.2 °F to 80.1 °F.

Relative Humidity

The relative humidity indoors ranged from 45.3 percent to 55.6 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 48.0 to 55.4 percent.

Ccu-bon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 426 ppm to 1261 ppm. All of the indoor measurements for CO2 were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 493 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1193 ppm (background level + 700 ppm). The highest reading (1261 ppm) was measured in room # 507 around 8:30 A.M. 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 1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were also 1 ppm for all readings..

Respirable Particulates (PM2,s)

Respirable particulate concentrations* indoors ranged between 14 pg/m^ to 25 pg/m^ with an average of 20 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. Three (3) of the outdoor instantaneous measurements were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children.

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