NYC-WTC_000214968

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March 28,2002 Indoor Air Quality Assessment Page 3 P. S. 150M ATC Project No. 15-19125-0289

REAL-TIME ENVIRONMENTAL MEASUREMENTS

ATC collected forty (40) sets of real-time environmental measurements consisting of thirty (30) from inside the school building and ten (10) from outdoors. All three floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 2:15 P.M. and concluded at approximately 3:35 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 69.9°F to 76.8°F. One (1) of the measurements was above the range of 68 to 75 °F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 50.5°F to 52.0°F.

Relative Humidity

The relative humidity indoors ranged from 26.9 to 32.3 percent. Seven (7) of the measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 36.6 to 38.9 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 409 ppm to 535 ppm. All of the CO2 measurements were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 405 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1105 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 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 indoor concentrations were 0 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration was 0 ppm for all collected readings.

Respirable Particulates (PM2_5) ppm.

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 16 pg/m^. None of the measurements were above the NPAAQS of 65 pg/m or above the USEPA recommendation of 40 pg/m^ for sensitive individuals and children. The average PM2.5 concentration for the entire school building was approximately 10 pg/m^. The PM2.5 average concentration was below the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration measurements ranged from 9 to 14 pg/m3 with an average of 10 pg/m3.

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