NYC-WTC_000211016

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 11, 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 (70) from inside the school building and ten (10) from outdoors. All five floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment I. Readings began at 8;00 A.M. and concluded at approximately 10:40 A.M.

reniperature

Indoor dry bulb temperature measurements ranged from 71.0 °F to 75.1 °F. Thirteen (13) of the indoor measurements for temperature were below the range of 73 to 79°F (at 50 percent relative humidity) a.s recommended by the ASHRAF Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 75.1 °F to 75.4 °F.

Relative Humidity

The relative humidity indoors ranged from 42.1 to 56.4 percent. All of the indoor measurements for relative humidity were within the ASHRAE-rccommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 60.8 to 60.9 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 505 ppm to 1410 ppm. Three (3) of the indoor measurements for CO2 were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 564 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1264 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 were 1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE. guideline of 9 ppm. The outdoor CO concentrations were 1 ppm for all collected readings.

Rexpirable Particulates (PM2,j}

Respirable particulate concentrations* indoors ranged between 10 pg/m^ to 30 pg/m^. The average PM2.5 concentration for the entire school building was approximately 21 pg/m^. All of the indoor measurements were below 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. The outdoor respirable particulate concentration measurements ranged between 35 pg/m^ to 40 g/m^ with an average of 38 pg/m^.

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NYC-WTC_000211018