NYC-WTC_000199187

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 12,2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATC Project No. 15-19125-0279

Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty-one (51) from inside the school building and nine (9) 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 2:00 P.M. and concluded after 3:55 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 68.9 °F to 76.1 °F. Twenty-seven (27) indoor measurements for temperature were above and twenty-four (24) were within 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 55.3 to 59.6 °F.

Relative Humidity

The relative humidity indoors ranged from 28 percent to 34.4 percent. Thirty (30) indoor measurements for relative humidity were below and twenty-one (21) were within the ASHRAE- recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 25.9 to 34.9 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 480 ppm to 1250 ppm. One (1) of the indoor measurements was below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 487 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1187 ppm (background level -1- 700 ppm). The highest reading was taken in room 380 (1250 ppm) at 2:20 PM with 19 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 1-2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were 1 ppm for all readings.

Respirable Particulates (PM2_5)

Respirable particulate concentrations* indoors ranged between 10 pg/m^ to 28 pg/m^. None of the indoor or outdoor measurements for PM2.5 were above 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.

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NYC-WTC_000199189