NYC-WTC_000215155

NYC 9/11 Public Portal Document

Mr.’Bernard P. Orlan February 18, 2002 Indoor Air Quality Assessment Page 3 H.S. for Leadership & Pub. 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 thirty-four (134) in the school building and six (6) outdoors. All fourteen floors of the school were surveyed. Field data sheets are found in the Attachment. Readings began at 8:35 A.M. and concluded after 3:40 P.M. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 64.8°F to 78.1 °F. Six (6) of the measurements were below and fifteen (15) were above the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAF Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature range was 47.4°F to 53.3°F.

Relative Humidity

The relative humidity indoors ranged from 22.6 percent to 39.3 percent. One hundred and thirty- two (132) measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 25,2 to 31.2 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 487 ppm to 1028 ppm. All of the measurements were within the ASHRAF Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concenfrations ranged from 459 ppm to 506 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1206 ppm (background level + 700 ppm). The highest reading was recorded in Room B06 at around 3:40 P.M. 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 COg indoors is occupant respiration.

Carbon Monoxide Concentration

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

Respirable Particulates (PM2j)

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 pgAn 3 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. The outdoor respirable particulate concentrations ranged from 39 pg/m^ to 84 pg/m^ with an average of 57 pg/m^.

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

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NYC-WTC_000215157