NYC-WTC_000189753

NYC 9/11 Public Portal Document

Mr Bernard P Orlan February 28, 2002 Indoor Air Quality Assessment Page 3 H S for Leadership & Pub Service (M894) ATCProiectNo 15-19125-0290

Real-Time Environmental Measurements

ATC collected one hundred and forty-one (141) sets of real-time environmental measurements consisting of one hundred and thirty-six (136) in the school building and five (5) outdoors All fourteen floors of the school were surveyed Field data sheets are found in the Attachment Readings began at 8 17 AM and concluded after 1 43 P M The results are described below

Temperature

Indoor dry bulb temperature measurements ranged from 66 8°F to 74 9°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 41 7°F to 54.5°F

Relative Humidity

The relative humidity indoors ranged from 29 percent to 30 8 percent 24 readings were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 28 6 to 40 percent

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 375 ppm to 1064 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 332 ppm to 599 ppm Therefore, the maximum acceptable level of CQ2 at this location was 1108 ppm (background level + 700 ppm). The highest reading was recorded in Room 515 at around 1 03 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 CO2 indoors is occupant respiration.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors were 1-2 ppm These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm The outdoor CO concentrations were 2-4 ppm

Respirable Particulates (PM2 5)

Respirable particulate concentrations* indoors ranged between 2 pg/m^ to 37 pg/m^ with an average 9 pg/m^ None of the measurements were above the NPAAQS of 65 pg/m3 24-hour average concentration of particulate matter 2.5 micrometers or less m aerodynamic diameter. The outdoor respirable particulate concentrations ranged from 51 pg/m^ to 95 pg/m^ with an average of 66 ug/m^

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

CITY_21MC100_006797807

NYC-WTC_000189755