NYC-WTC_000215187

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March 1, 2002 Indoor Air Quality Assessment - Page 3 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 11:10 A.M. and concluded after 7:43 P.M. The results are described below.

Temperatu7'e

Indoor dry bulb temperature measurements ranged from 60.9°F to 75.0°F. Ten (10) were below 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 42.9°Fto58.7°F.

Relalive Humidity

The relative humidity indoors ranged from 18.4 percent to 42.5 percent. Eight (8) measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. All other relative humidity measurements were below the ASRAE recommended range. The outdoor relative humidity range was 18.4 to 42.5 percent.

Carbon Dioxide Conceniration

Carbon dioxide concentrations indoors ranged from 423 ppm to 984 ppm. None of the measurements were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentrations ranged from 267 ppm to 521 ppm. Therefore, the maximum acceptable level of CQ2 at this location was 1221 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 Conceritration

Carbon monoxide concentrations indoors were 0-2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations,were 1-3 ppm.

Respirable Particulates CPM2^

Respirable particulate concentrations* indoors ranged between 1 pg/m^ to 28 pg/m^ with an average 7 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 outdoor respirable particulate concentrations ranged from 18 pg/m^ to 71 pg/m^ with an average of 44 pg/m^.

* The measurements made during this assessment were instantaneous readings, the NPAAQS is a 24-hour average.

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NYC-WTC_000215189