NYC-WTC_000214406

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 13,2002 Indoor Air Quality Assessment Pages 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 (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 1:05 P.M. and concluded at approximately 2:26 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 72.3 °F to 79.3 °F. One (1) of the indoor measurements was below and five (5) indoor measurements were above the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAF Standard 55-1992 during the mechanical cooling season (summertime conditions).The outdoor temperature measurements ranged from 87.0 °F to 88.4 °F.

E^lotiyeHumiditv

The relative humidity indoors ranged from 42.5 to 58.6 percent. All of the measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 52.1 to 52.4 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 561 ppm to 1362 ppm. One (1) of the CO2 indoor measurements was above the ASHRAF Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 561 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1261 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.

Carbon Monoxide Concentration

Carbon monoxide indoor concentrations were 1 ppm for all collected readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were also 1 ppm for all collected readings.

Respirable Particulates (PM2,s) PP^-

Respirable particulate concentrations* indoors ranged between 16 pg/m- to 56 pg/m^. None of the indoor measurements were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Four (4) of the indoor measurements were above the USEPA recommendation of 40pg/m3 for sensitive individuals and children. The average PM2.5 concentration for the entire school building was approximately 30 pg/m3. The outdoor respirable particulate concentration measurements ranged from 83 to 91 pg/m^ with an average of 88 pg/m-.

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NYC-WTC_000214408