NYC-WTC_000189397

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan -April 10, 2002 Indoor Air Quality Assessment Pages H.S. for Leadership & Public Service (M894) ATC Project No. 15-19125-0290 Real-Time Environmental Measurements

ATC collected one hundred and forty (140) sets of real-time environmental measurements consisting of one hundred and twenty-eight (128) in the school building and twelve (12) outdoors. All fourteen floors of the school were surveyed. Field data sheets are found in the Attachment. Readings began at 10:45 A.M. and concluded after 1:50 P.M. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 70.3 °F to 77.5 “F. One hundred and ten (110) indoor measurements for temperature were above the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature range was 68.5 °F to 73.4 °F.

Re!ali\’e /■fumidiiy

The relative humidity indoors ranged from 42.2 percent to 52.9 percent. All of the indoor measurements for relative humidity were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 40.9 to 49.2 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 419 ppm to 1410 ppm. Two (2) the indoor measurements for CO2 were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 422 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1122 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 outdoor air. The primary source of CO2 indoors is occupant respiration.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors ranged from 0 ppm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 2 ppm- 4 ppm.

Respirable Particulates (PM2_s)

Respirable particulate concentrations* indoors ranged between 2 gg/m^ to 36 pg/m^ with an average 6 pg/m^- All of the indoor measurements for PM2,5 were below the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter and the USEPA recommended concentration of 40 pg/m^ for sensitive individuals such as asthmatic people and children. The outdoor respirable particulate concentrations ranged from 36 pg/m^ to 54 pg/m^ with an average of 43 pg/m^. Six (6) of the twelve (12) instantaneous outdoor measurements were above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals such as asthmatic people and children.

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