NYC-WTC_000207966

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan August 29, 2002 Indoor Air Quality Assessment Page 3 P.S.2M ATC Project No. 15-19125-0341

Real-Time Environmental Measurements

ATC collected fifty (50) sets of real-time environmental measurements consisting of forty-eight (48) in the school building and two (2) outdoors. All floors of the school were surveyed. Field data sheets are found in the Attachment. Readings were collected during school hours. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 81.9 to 87.1 °F. All indoor measurements 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 measurements were 81.6 and 82.2 °T collected before and after the indoor samples.

Relative Humidity

The relative humidity indoors ranged from 41.6 percent to 62.4 percent. Four (4) of the indoor measurements for relative humidity were slightly above the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements were 61.6 and 61.8 percent collected before and after the indoor samples.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 642 ppm to 1210 ppm. All indoor measurement for COg were below the ASIIRAE Standard 62-2001 recommended maximum concentration of <700 ppm above the background level. The average outdoor (background) CO2 concentration was 559 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1259 ppm (background level + 700 ppm). 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 2 ppm to 3 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The average outdoor CO concentrations was 2 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 33 pg/m^ to 49 pg/m^. All indoor measurements collected 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. Thirty one (31) of the forty-eight (48) instantaneous indoor readings were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals such as asthmatic people and children. The two outdoor respirable particulate concentrations were 58 pg/m^ and 57 pg/m^ with an average of 57,5 pg/m^. Both outdoor 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.

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