NYC-WTC_000205292

NYC 9/11 Public Portal Document

05/06/2/)02 11:29 PAX 212 353 8306 ATC 121004

Mr. Bernard P, Orlan May 6,2002 Indoor Air Quality Assessment Page 3 j P. S. 89M ATC Project No. 15 19125-0297

Real-; Envtronmental 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 11:30 A.M.

Tsmverature

Indoor dry bulb temperature measurements ranged from 70.1 °F to 73.8 °F. Sixty-two (62) 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 die summer season . The outdoor temperature measurements ranged from to 60.9°F.

Relative Humidity

The relative humidity indoors ranged from 24.8 to 32.2 percent. Thirty-eight (38) of the indoor measurements for relative humidity were below and thirty-two (32) were within the ASHRAF- recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 31.6 to 31,9 percent.

Carbon Diaxids Concentration

Carbon dioxide concentrations indoors ranged from 471 ppm to 1416 ppm. Ten (10) 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 473 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1173 ppm (background level + 700 ppm). The highest reading (1416 ppm) was taken in room 404 at 9:54 AM with 31 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 Afonoxide 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 concentration were also 1 ppm for all collected readings.

Respirable Particulate,^ (P^2.s)

Respirable particulate concentrations* indoors ranged between 14 (ig/tn^ to 20 pg/m^. The average PM2.5 concentration for the entire school building was approximately 17 g/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/m3 for sensitive individuals and children. The outdoor

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