NYC-WTC_000199202

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 22,002 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 P.M. and concluded after 4:10 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 71.9 °F to 78.4 °F. Twelve (12) indoor measurements for temperature were below the range and thirty-nine (39) measurements were within the range of 73 to 79°F (at 50 percent relative humidity) as recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 70.9 to 82.5 °F.

Relative Humidity

The relative humidity indoors ranged from 40 percent to 55 percent. All indoor measurements for relative humidity were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 45.Ito 53 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 555 ppm to 820 ppm. All of the measurements were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 500 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1200 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 2 ppm to 3 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm .The outdoor CO concentrations were 2 ppm.

Respirable Particulates (PM2.51

Respirable particulate concentrations* indoors ranged between 19 pg/m^ to 60 pg/m^ with an average 37 pg/m^- All measurements collected indoors for respirable particulate concentrations are below the NPAAQS 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Sixteen (16) of the fifty-one (51) instantaneous indoor readings were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration ranged from 55 pg/m^ to 96 pg/m^ with an average of 64 pg/m^.

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NYC-WTC_000199204