NYC-WTC_000223592

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 25,2002 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 in the morning and in the evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 78.4 °F to 84.7 °F. Ninety-two (92) of the indoor measurements for temperature were above the range of 73 °F to 79°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 83.3 °F to 89.6 °F.

Relative Humidity

The relative humidity indoors ranged from 39.8 percent to 56.3 percent. All of the indoor measurements for relative humidity were within ASHRAE recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 60.1 to 64.0 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 460 ppm to 849 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 529 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1229 ppm (background level + 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 indoors ranged from 1 ppm to 2 ppm. These concentrations were within the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 1 ppm to 3 ppm.

Respirable Particulates (PM2_§)

Respirable particulate concentrations* indoors ranged between 12 pg/m^ to 112 pg/m^ with an average of 30 pg/m^- Nine (9) 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 and above the USEPA recommended concentration of 40 pg/m3 for sensitive individuals and children. The respirable concentration outdoors ranged between 123 pg/m3 to 169 pg/m^ with an average of 150 pg/m^ •

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

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NYC-WTC_000223594