NYC-WTC_000199027

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 23, 2002 Indoor Air Quality Assessment Page 3 P. S. 89M_______________________________ ATC Project No. 15-19125-0297 Real-Time Environmental Measurements

ATC collected seventy-nine (80) sets of real-time environmental measurements consisting of seventy-one (71) from inside the school building and nine (9) from outdoors. All five floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 8:00 A.M. and concluded at approximately 11:30 A.M.

Temperature

Indoor dry bulb temperature measurements ranged from 67.5°F to 74 °F. Fifty-eight (58) of the indoor measurements for temperature were below the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the summer season . The outdoor temperature measurements ranged from 59.6 °F to 60.3 °F.

Relative Humidity

The relative humidity indoors ranged from 26.3 to 32.3 percent. Sixty-two (62) 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 measurements ranged from 33.1 to 34.0 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 544 ppm to 1199 ppm. All of the indoor measurements for CO2 were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 568 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1268 ppm (background level + 700 ppm). Carbon dioxide measurements are used as an indicator of available outside makeup air. The primary source of CO2 indoors is occupant respiration. The school building was occupied during ATC’s assessment.

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 were 2 ppm for all collected readings.

Respirable Particulates (PM2j)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 20 pg/m^. The average PM2.5 concentration for the entire school building was approximately 11 pg/m^. All of the indoor measurements were below the NPAAQS of 65 pg/m3 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 outdoor respirable particulate concentration measurements ranged from 23 to 26 pg/m^ with an average of 24 pg/m^.

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NYC-WTC_000199029