NYC-WTC_000220651

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 18, 2002 Indoor Air Quality Assessment Page 3 P. S. 89M ATC Project No. 15-19125-0297

Real-Time Environmental Measurements

ATC collected eighty (80) sets of real-time environmental measurements consisting of seventy (70) from inside the school building and ten (10) from outdoors. All five floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 8:00 A.M. and concluded at approximately 11 ;300 A.M.

Temperature

Indoor dry bulb temperature measurements ranged from 77.7 °F to 84.0 °F. Sixty (60) of the indoor measurements for temperature were above and ten (10) were within the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 80 to 82.7 °F.

Relative Humidity

The relative humidity indoors ranged from 41.5 to 50.9 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 measurements ranged from 42.1 to 44.5 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 641 ppm to 1176 ppm. All of the indoor measurements were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 619 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1319 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 outside makeup air. The primary source of CO2 indoors is occupant respiration. The school building was occupied during ATC’s assessment.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors were 2 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration was 7 ppm for all collected readings.

Respirable Particulates (PM2 §)

Respirable particulate concentrations* indoors ranged between 14 pg/m^ to 107 ug/m^. The average PM2.5 concentration for the entire school building was approximately 74 g/m^. Forty- nine (49) of the indoor measurements were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Seventy- five (75) of the eight (80) indoor instantaneous measurements were above the USEPA

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NYC-WTC_000220653