NYC-WTC_000223920

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 10,2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATCPrpicctNcU5d9i2>02Z9

Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty (50) from inside the school building and ten (10) 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 7:00 A.M. and concluded after 12:40 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 70.1 °F to 73.7°F. Forty-four (44) indoor measurements for temperature were below the range of 73 to 79°F (at 50 percent relative humidity) as recommended by ASHRAF Standard 55-1992 during the summer season. The outdoor temperature measurements ranged from 54.1 to 54.4 °F.

Relative Humidity

The relative humidity indoors ranged from 38.6 percent to 42.6 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 43.1 to 43.2 percent.

CarbonDioxideConcentration

Carbon dioxide concentrations indoors ranged from 410 ppm to 1242 ppm. One (l)of the measurements was above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 449 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1149 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 were 2 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were 1 ppm for all readings.

Respirable Particulates (PM2j)

Respirable particulate concentrations* indoors ranged between 10 pg/m^ to 22 ug/m^ with an average approximately 18 pg/m^- All measurements collected indoors for respirable particulate concentrations were below the NPAAQS 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter or the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration ranged from 16 pg/m^ to 24 pg/m^ with an average of approximately 22 pg/mY

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