NYC-WTC_000202383

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan September 10, 2002 Indoor Air Quality Assessment Page 3 P.S. 42 M ATC ProiectNo. 15-19125-0342

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 diy bulb temperature measurements ranged from 72.0 to 76.4 °F. Six (6) of the indoor temperature measurements were below 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 75.7 and 82.7 °F.

Relative Humidity

The relative humidity indoors ranged from 47.9 percent to 76.1 percent. Twelve (12) of the indoor measurements for relative humidity were above the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements were 58.4 and 58.7 percent. The high ambient relative humidity likely contributed to the elevated particulate levels reported below.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 636 ppm to 1396 ppm. One (1) of indoor measurement for CO2 was above the ASHRAE Standard 62-2001 recommended maximum concentration of <700 ppm above the background level. The average outdoor (background) COg concentration was 681 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1381 ppm (background level + 700 ppm). Carbon dioxide measurements are used as an indicator of available outdoor air. The primary source of COp 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 were 2 ppm and 3ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 33 pg/m^ to 96 pg/m^. Forty- five (45) of the indoor measurements collected for PMpy 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 182 pg/m^ and 65 pg/m^ with an average of 124 pg/m3. The Dust Trak® detects volatile aerosol particles and may be affected by elevated humidity and airborne moisture droplets in addition to dust particles.

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NYC-WTC_000202385