NYC-WTC_000199192

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan Apnl 18,2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATC Project No. 15-19125-0279

Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty-one (51) from inside the school building and nine (9) outdoors. All three floors of the school were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 2:00 P.M. and concluded after 4:30 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 72.4 °F to 79.3 °F. Two (2) indoor measurements for temperature were above and eight (8) measurements were bellow the range of 73 to 79°F (at 50 percent relative humidity) as recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 81.3 to 87.3 °F.

Relative Humidity

The relative humidity indoors ranged from 38.7 percent to 51.9 percent. All indoor measurements for relative humidity were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 39.0 to 49.0 percent.

CcmbonJ)iwddeConcentration

Carbon dioxide concentrations indoors ranged from 703 ppm to 1118 ppm. All of the 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 680 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1380 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.

CarbonMonoxide Concentration

Carbon monoxide concentrations indoors were 2ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 2 to 7 ppm.

Respirable Particulates (PM2.5)

Respirable particulate concentrations* indoors ranged between 35 pg/m^ to 119 pg/m^ with an average 70 pg/m^- Twenty nine(29) of the indoor measurements for respirable particulates were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter and forty six (46) indoor measurements were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The

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NYC-WTC_000199194