NYC-WTC_000199221

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 7, 2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATCPrpiectNpJ^21912520279 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 AM and concluded after 12:46 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 72,4 °F to 75.8 °F, Six (6) of the indoor measurements for temperature were below 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 74,2 °F to 74,5 °F,

Relative Humidity

The relative humidity indoors ranged from 51,6 percent to 61,1 percent. Two (2) 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 ranged from 68,0 percent to 68,2 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 561 ppm to 1162 ppm. All of the indoor measurements were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 563 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1263 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 also 2 ppm for all readings.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 8 pg/m^ to 28 pg/m^ with an average approximately 16 pg/m^- None of the measurements collected indoors for respirable particulate concentrations were above the NPAAQS 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter and the USEPA recommended concentration of 40 pg/m^ for sensitive individuals and children. The outdoor respirable particulate concentration ranged from 108 pg/m^ to 112 pg/m^ with an average of approximately 110 pg/m^.

* The measurements made during this assessment were instantaneous readings, the NPAAQS is a 24-hour average.

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NYC-WTC_000199223