NYC-WTC_000211863

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March 28, 2002 Indoor Air Quality Assessment Page 3 H.S. for Leadership & Public Service fM894) ATC Project No. 15-19125-0290 Real-Time Environmental Measurements

ATC collected one hundred and forty (140) sets of real-time environmental measurements consisting of one hundred and twenty-eight (128) in the school building and twelve (12) outdoors. All fourteen floors of the school were surveyed. Field data sheets are found in the Attachment. Readings began at 8:01 A.M. and concluded after 3:2.1 P.M. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 73.2 °F to 78.8 °F. One hundred and seventeen (117) indoor measurements for temperature were above and eleven (11) measurements were within the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature range was 59.4 °F to 62.4 °F.

Relative Humidity

The relative humidity indoors ranged from 28.4 percent to 38.3 percent. Fifty (50) of the indoor measurements for relative humidity were below and seventy-eight (78) measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 27.2 to 35.7 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 467 ppm to 781 ppm. All of the indoor measurements for CO2 were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 486 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1186 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 ■ outdoor air. The primaiy source of CO2 indoors is occupant respiration.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors ranged from 1 ppm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 3 ppm- 4 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 2 pg/m^ to 33 pg/m^ with an average 5 pg/m^- All of the indoor measurements for PM2.5 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 such as asthmatic people and children. The outdoor respirable particulate concentrations ranged from 27 pg/m^ to 89 pg/m^ with an average of 59 pg/m^. Five (5) of the outdoor measurements for PM2.5 were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Nine (9) of

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