NYC-WTC_000187677

NYC 9/11 Public Portal Document

Mr, Bernard P. Orlan March 19, 2002 Indoor Air Quality Assessment Page 3 LJJ50m___________ ATC Project No. 15-19125-0289

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,4 FC 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 al 2:00 P.M. and concluded at approximately 3:50 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 70.9°F to 78.7°F. Four (4) 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 36.4 to 39.9'’F.

Relative Humidity

ddie relative humidity indoor.s ranged from 28.1 to 37.1 percent. Nine (9) of the measurements were below the ASlIRAE-recommended range of 30 to 60 percent for occupant comfort. Hie outdoor relative humidUy measurements ranged from 46.0 to 49.0 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 475 ppm to 680 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) CO2 concentration was 440 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1140 ppm (background level + 700 ppm). Levels above the recommended maximum do not indicate a health risk. Carbon dioxide measurements are used as an indicator (>f available outside makeup air. The primaiy' source of CO2 indoors is occupant respiration. 'Ilie school building was occupied during ATC’s assessment.

Carbon MonoxideCpn^ntration

Carbon monoxide concentrations were 0 ppm 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 (PMt, 5)

Respirable particulate concentrations* indoors ranged between 12 pg/m^ to 22 pg/m^. None of the indoor 0:’ outdoor measurements were above the NPAAQS of 65 pg/m^ or above the USEP.A. recommendation of 40 pg/m^ for sensitive individuals and children. Thie 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 f rom 16 to 20 pg/m^ with an average of 18 pg/m^.

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NYC-WTC_000187679