NYC-WTC_000223596

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 26,2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance (M833)________ MCPrpiectNpJM912S0291 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 75.1 °F to 83.6 °F. Fifty (50) 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 82.2 °F to 86.1 °F.

Relative Humidity

The relative humidity indoors ranged from 38.0 percent to 52.1 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 47.8 to 53.6 percent.

CarbonDioxi^ Concentration

Carbon dioxide concentrations indoors ranged from 512 ppm to 836 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 601 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1301 ppm (backgroimd 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 0 ppm to 2 ppm.

Respirable Particulates (PM2 j)

Respirable particulate concentrations* indoors ranged between 4 pg/m^ to 55 pg/m^ with an average of 14 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. Five (5) of the indoor measurements were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The respirable concentration outdoors ranged between 26 pg/m^ to 71 pg/m^ with an average of 54 pg/m^ •

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

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