NYC-WTC_000188373

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 14,2002 Indoor Air Quality Assessment Page 3 U.S. for Leadershin & Public Service (M894) 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 were collected in the morning and evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 69.3 °F to 79.9 °F. One-hundred and twenty-five (125) of the indoor measurements for temperature were below and two (2) were within 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 60.9 to 61.9°F.

Relative Humidity

The relative humidity indoors ranged from 49.1 percent to 58.5 percent. All of the indoor measurements for relative humidity were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 44.6 to 79.6 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 416 ppm to 1126 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 473 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1173 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 ranged from 1 to 2 ppm. These concentrations were below the NPAAQSZASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 1 to 2 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 8 pg/m^ to 29 pg/m^ with an average 17 pg/m^- All the indoor measurements for PM2.5 were within 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 26 pg/m^ to 34 pg/m^ with an average of 30 pg/m^.

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NYC-WTC_000188375