NYC-WTC_000219896

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 31,2002 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 and six (106) sets of real-time environmental measurements consisting of ninety-four (94) 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 78.0 °F to 82.7 °F. Ninety-one (91) of the indoor measurements for temperature were above and none of the measurements were below the range of 73 to 79°F (at 50 percent relative humidity) recommended by ASHRAF Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 75.9 °F to 81.9 °F.

Relative Humidity

The relative humidity indoors ranged from 40.2 percent to 57.4 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 50.6 to 64.3 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 484 ppm to 1488 ppm. One (1) of the indoor measurements for CO2 was above the ASHRAF Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 642 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1342 ppm (background level + 700 ppm). The highest concentration was recorded in room 306 at 12:20 PM with 27 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 ranged from Ippm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 1 ppm to 3 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 4 pg/m^ to 28 pg/m^ with an average of 12 pg/m^- None of the indoor measurements for respirable particulates were above the NPAAQS of 65 pg/m3 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter or above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The respirable concentrations outdoors ranged between 31 pg/m^ to 72 pg/m^ with an average of 51 pg/m3 •

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

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NYC-WTC_000219898