NYC-WTC_000223588

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 24,2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance (M833)________ ATCPrQiectNoaM9125-0291 Real-Time 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 morning to evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 69.9 °F to 81.6 °F. Twenty-six (26) of the indoor measurements for temperature were below and eighteen (18) indoor temperature 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 60.1 °F to 73.9 °F.

Relative Humidity

The relative humidity indoors ranged from 27.6 percent to 44.6 percent. Four (4) of the indoor measurements for relative humidity were below and none of the readings were above the ASHRAE recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 29.9 to 34.4 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 542 ppm to 1541 ppm. Sixteen (16) 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 547 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1247 ppm (background level + 700 ppm). The highest reading was taken in room 307 at 10:30 AM with 25 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 was 1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations was 1 ppm for all collected readings.

Respirable Particulates (PM2_§)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 22 pg/m^ with an average of 12 pg/m^- None of the indoor measurements for respirable particulates were above the NPAAQS of 65 pg/m^ 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 36 pg/m3 with an average of 33 pg/m3 ■

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