NYC-WTC_000199010

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 9, 2002 Indoor Air Quality Assessment Page 3 P. S. 89M ATC Project No. 15-19125-0297

Real-Time Environmental Measurements

ATC collected eighty (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 1. Readings began at 8:00 A.M. and concluded at approximately 11:15 A.M.

Temperature

Indoor dry bulb temperature measurements ranged from 72.1 °F to 75.5 °F. Seventeen (17) 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 64.9°F to 65.7 °F.

Relative Humidity

The relative humidity indoors ranged from 37.5 to 47.8 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 measurements ranged from 44.5 to 45.1 percent.

Carbon Dioxide Concentration

Carbon dioxide concenPations indoors ranged from 451 ppm to 1261 ppm. Two (2) of the indoor measurements for CO2 were above the ASHRAE Standard 62-1999 recommended maximum concenPation of <700 ppm above the background level. The maximum outdoor (background) CO2 concenPation was 470 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1170 ppm (background level -1- 700 ppm). The highest reading (1261 ppm) were taken in room 508 at 8:40 AM with 32 occupants. 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 concentrations indoors were 1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concenPation were 1 ppm for all collected readings.

Respirable Particulates (PM2_3)

Respirable particulate concentrations* indoors ranged between 12 pg/m^ to 26 pg/m^. The average PM2.5 concentration for the entire school building was approximately 20 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 concenPation of 40 pg/nU for sensitive individuals and children. The outdoor

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