NYC-WTC_000189316

NYC 9/11 Public Portal Document

Mr Bernard P Orlan March 22 2002 Indoor Air Quality Assessment Page 3 H S for Leadershir & Public Service (M894) ATCProiectNo 15 19125 0290 Real Time Environmental Measurements ATC collected one hundred and thirty seven (137) sets of real time environmental measurements consisting of one hundred and twenty eight (128) in the school building and nme (9) outdoors All fourteen floors of the school were surveyed Field data sheets are found in the Attachment Readings began at 10 17 AM and concluded after 6 03 P M The results are described below

Temrierature

Indoor dry bulb temperature measurements ranged from 65 2 °F to 79 2 °F Ninety six (96) indoor measurement for temperature were above and thirty one (31) measurements were within the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55 1992 dunng the heating season (wintertime conditions) The outdoor temperature range was 55 7 °F to 60 9 °F

Relative Humidity

The relative humidity indoors ranged from 25 percent to 34 2 percent Ninety nine (99) of the indoor measurements for relative humidity were below and twenty nine (29) were within the ASHRAE recommended range of 30 to 60 percent for occupant comfort The outdoor relative humidity range was 25 1 to 29 9 percent

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 436 ppm to 1233 ppm One of the mdoor measurements for CO2 was above the ASHRAE Standard 62 1999 recommended maximum concentration of <700 ppm above the background level The outdoor (background) CO2 concentration was 468 ppm Therefore the maximum acceptable level of CO2 at this location was 1168 ppm (background level + 700 ppm) The highest reading (1233 ppm) was measured in room 815 at 2 42 PM with 38 occupants Levels above the recommended maximum do not mdicate 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 1 ppm to 2 ppm These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm The outdoor CO concentrations ranged from 3 ppm 5 ppm

Respirable Particulates (PM2 j)

Respirable particulate concentrations* indoors ranged between 11 pg/m^ to 41 pg/m^ with an average 18 pg/m^ All of the indoor measurements for PM2 5 were below the NPAAQS of 65 pg/m3 24 hour average concentration of particulate matter 2 5 micrometers or less in aerodynamic diameter One (1) of the one hundred thirty seven (137) instantaneous indoor readings was above the USEPA recommended concentration of 40 pg/m^ for sensitive individuals such as asthmatic people and children The outdoor respirable particulate concentrations ranged from 71 pg/m3 to 96 pg/m^ with an average of 87 pg/m^ All of the outdoor measurements were above the NPAAQS of 65 pg/m^ 24 hour average concentration of particulate matter 2 5 micrometers or less in aerodynamic diameter and the USEPA

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NYC-WTC_000189318