NYC-WTC_000212691

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan April 25,002 Indoor Air Quality Assessment Pages P. S. 234M______________________________ ATC Project No. 15-19125-0279 Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty-one (51) from inside the school building and nine (9) outdoors. All three floors of the school were surveyed, flrese results are described below.

Field data sheets are found in Attachment 1. Readings began at 2 P.M. and concluded after 4:10 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 54 °F to 73.8 °F. Forty-six (46) indoor measurements for temperature were below the range and five (5) measurement were within the range of 73 to 79°F (at 50 percent relative humidity) as recommended by ASHRAF Standard 55- 1992 during the summer season. The outdoor temperature measurements ranged from 56.1 to 68°F.

Relative Humidity

The relative humidity indoors ranged from 21.5 percent to 35.5 percent. Forty-three (43) indoor measurements for relative humidity were below and eight (8) measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity ranged from 21.8 to 29.1 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 490 ppm to 1109 ppm. All of the measurements were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 550 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1250 ppm (background level -1- 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 were 2 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations were 2 ppm for all leadings.

Respirable Particulates (PM2,5)

Respirable particulate concentrations* indoors ranged between 6 pg/m^ to 28 pg/m^ with an average 18 pg/m^- All measurements collected indoors and outdoors for respirable particulate concentrations were below the NPAAQS 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 and children. The outdoor respirable particulate concentration ranged from 12 pg/m^ to 17 pg/m^ with an average of 13 pg/m-h

CITY_21MC100_002851812

NYC-WTC_000212693