NYC-WTC_000194816

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan February 18,2002 Indoor Air Quality Assessment Page 3 P, S, 150M ATC Project No. 15-19125-0289

Real-Time Environmental Measurements

ATC collected forty (40) sets of real-time environmental measurements consisting of thirty-three (33) from inside the school building and seven (7) from outdoors. All three floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 12:00 P.M. and concluded at approximately 1:30 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 74.9°F to 79.0°F. Thirty-two (32) of the measurements were above the range of 68 to 75°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 42.0 to 42.6°F.

Relative Humidity

The relative humidity indoors ranged from 19.6 to 25.7 percent. All of the measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 24.4 to 25.9 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 545 ppm to 2040 ppm. Two (2) of the CO2 measurements were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 482 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1182 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.

CarbonJi{onoxideConcentratipn

Carbon monoxide concentrations indoors were 0 ppms for the interior readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration was also 0 ppm for all collected readings.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 12 pg/m^ to 20 pg/m^. None of the measurements were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. The average PM2.5 concentration for the entire school building was approximately 16 pg/m^. The PM2.5 average concentration was below the USEPA recommended concentration of 40 pg/m^ for sensitive individuals / children. The outdoor respirable particulate concentration measurements ranged from 23 to 26 pg/m^ with an average of 25 pg/m^.

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