NYC-WTC_000188381

NYC 9/11 Public Portal Document

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Mr. Bernard P. Orlan May 24, 2002 Indoor Air Quality Assessment Page 3 H.S. for Leadership & Public Service (M894) ATC. Project No. 15-19125-0290

Real-Time Enviromviental 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 were collected in the morning and evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 72.7°F to 78.6 °F. Three (3) of the indoor measurements for temperature were below and no readings were above the range of 73 to 79°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature ranged from 64.1 to 74.9°F.

Relative Humidity

The relative humidity indoors ranged from 26.1 percent to 34.1 percent. Nineteen (19) of the indoor measurements for relative humidity were below and no readings were above the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 29.1 to 38.9 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 501 ppm to 1211 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 609 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1309 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 primary source of CO2 indoors is occupant respiration.

Carbon Monoxide Concentration

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

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 17 pg/m^ with an average 12 pg/m^' None of the indoor measurements for PM2,5 were above the NPAAQS of 65 pg/m3 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 32 pg/m^ to 46 pg/m^ with an average of 39 pg/m^.

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NYC-WTC_000188383