NYC-WTC_000214370

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 1,2002 Indoor Air Quality Assessment Page 3 P. S. 15QM 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 12:30 P.M. and concluded at approximately 1:30 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 65.9°F to 76.7°F, Nine (9) of the measurements were below the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the heating season (summertime conditions). The outdoor temperature measurements ranged from 55.0°F to 58.3°F.

Relative Humidity

The relative humidity indoors ranged from 27.8 to 38.2 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 27.2 to 28.5 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 547 ppm to 1280 ppm. Two (2) of the CO2 measurements were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 535 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1235 ppm (background level -1- 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 wasoccupied during ATC’s assessment.

Carbon Monoxide Concentration

Carbon monoxide indoor concentrations were 1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration were also 1 ppm for all collected readings.

Respirable Particulates (PM2,3) ppm.

Respirable particulate concentrations* indoors ranged between 17 pg/m^ to 26 pg/m^. None of the indoor measurements were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter or the USEPA recommendation of 40pg/m3 for sensitive individuals and children. The average PM2.5 concentration for the entire school building was approximately 21 pg/m^. The outdoor respirable particulate concentration measurements ranged from 27 to 34 pg/m^ with an average of31pg/m3.

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NYC-WTC_000214372