NYC-WTC_000199183

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March 7, 2002 Indoor Air Quality Assessment Page 3 P. S. 234M______________________________ ATC Project No. 15-19125-0279 Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty-one (51) from inside the school building and nine (9) 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 12:00 P.M. and concluded after 1:55 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 70.2 °F to 78.0 °F. Eighteen (18) measurements were above the range of 68 to 75°F (at 50 percent relative humidity) as recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 37.3 to 44.3 °F.

Relative Humidity

The relative humidity indoors ranged from 17.0 percent to 21.0 percent. All of the measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 24.0 to 27.0 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 609 ppm to 907 ppm. All of the 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 520 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1220 ppm (background level + 700 ppm). The highest measurement was recorded in room 302. 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 0 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were also 0 ppm.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 13 pg/m^ to 22 pg/m^. All measurements were below 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 17 pg/m^. This average concentration was below the USEPA recommended concentration for sensitive individuals such as asthmatic people and children. The outdoor respirable particulate concentration ranged from 19 to 30 pg/m3 with an average of 21 pg/m^.

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NYC-WTC_000199185