NYC-WTC_000187689

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March (i. 2002 Indoor Air Quality Assessment Page 3 P. S. 150M ATC Proiect No. 15-19125-0289

Real-Time Enmronmental Measurements

ATC collected forty (40) sets of real-time environmental measurements consisting of thirty- (30) From inside the school building and ten (10) 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 2:00 P.M. and concluded at approximately 3:30 P.M.

Temperatiii-e.

Indoor dry bulb temperature measurements ranged from 74.8°F to 79.0°F. Twenty-eight (2.8) 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 32.0 to 33.6°F.

Rc/alive Hitmidiiy

Ihe relative humidity indoors ranged from 8.0 to 13.4 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 12.1 to 15.0 percent.

Curhnn Diaxide Concentration

Carbon dioxide concentrations indoors ranged from 585 ppm to 909 ppm. .All of the CO2 measurements were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO? concentration was 493 ppm. Therefore, the maximum acceptable level of COg at this location was 1193 ppm (background level + 700 ppm). Levels above the recommended maximum do not indicate a health nsk. Carbon dioxide measurements are used as an indicator of available outside makeup air. The primary source of CO2 indoors is occupant respiration. lire school building was occupied during ATC’s assessment.

Carbon AdonoxideC^centration

('arbon monoxide concentrations were 0 ppm for the interior readings. These concentrations were below the NP.AAQS/ASHRAE guideline of 9 ppm. Tire outdoor CO concentration was 0 ppm for all collected readings.

Jiespirahle Particulates (PM?,

Respirable particulate concentrations* indoors ranged between 12 pg/m^ to 27 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 axerage PM2.5 concentration for the entire school building was approximately 17 pg/m^. The PM? 5 average concentration was below the USFP.A recommended concentration of 40 pg/m^ for sensitixe individuals / children, flic outdoor respirable particulate concentration measurements ranged from 1S to 24 pg/m^ w:ith an average of 21 pg/m^.

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NYC-WTC_000187691