NYC-WTC_000199173

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan February 13, 2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATC Project No. 15-19125-0279

Real-Time Environmentai^Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of forty-nine (49) from inside the school building and eleven (11) outdoors. All three floors of the school were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 10:00 A.M. and concluded after 3:55 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 66.3 °F to 71.4 °F. Eight (8) measurements were below the range of 68 to 75°F (at 50 percent relative humidity) as recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 35.0 to 40.0 °F.

Relative Humidity

The relative humidity indoors ranged from 15.1 percent to 38.0 percent. Only one (1) of the measurements was within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. All other measurements were below the recommended range. The outdoor relative humidity ranged from 16.8 to 18.5 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 577 ppm to 3406 ppm. Ten (10) CO2 measurements were above the ASHRAF Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 480 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1180 ppm (background level + 700 ppm). The highest measurement was recorded in room 305. 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 were 0 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were also 0 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 20 pg/m^. All measurements were below the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. The average PM2.5 concentration for the entire school building was approximately 12 pg/m^. This average concentration was below the USEPA recommended concentration for sensitive individuals such

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