NYC-WTC_000223584

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 16, 2002 Indoor Air Quality Assessment Page 3 H.S. of Economics and Finance (M833)________ ATCProiectNoM549125-02^ 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 71.1 °F to 82.2 °F. Ten (10) of the indoor measurements collected were below and twenty (20) 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 64.6 °F to 73.6°F.

Relative Humidity

The relative humidity indoors ranged from 24.6 percent to 40.1 percent. Twenty-one (21) of the indoor measurements for relative humidity were below the ASHRAE recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 20.1 to 29.8 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 401 ppm to 1261 ppm. Five (5) 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 510 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1210 ppm (background level + 700 ppm). The highest reading was measured in room 509 at 2:16 PM with 22 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 1 ppm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 1 ppm to 2 ppm.

Respirable Particulates (PM2, j/

Respirable particulate concentrations* indoors ranged between 5 pg/m^ to 36 pg/m^ with an average of 16 pg/m^- All of the indoor 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 and the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The respirable concentrations outdoors ranged between 14 pg/m3 to 33 pg/m^ with an average of 26 pg/m^- * The measurements made during this assessment were instantaneous readings, the NPAAQS is a 24-hour average.

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NYC-WTC_000223586