NYC-WTC_000188389

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 26, 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 ?\ttachment. Readings were collected in the morning and evening. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 78.1 to 82.2 ’F. One hundred and four (104) of the indoor measurements were above the range of 73 to79 °F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the summer season. The outdoor temperature ranged from 82.6 to 89.2 °F.

Relative Humidity

The relative humidity indoors ranged from 40.9 percent to 56.2 percent. All of the indoor measurements for relative humidity were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 40.5 to 51.6 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 515 ppm to 754 ppm. All of the indoor measurements for CO2 were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) CO2 concentration was 589 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1289 ppm (background level + 700 ppm). 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 within the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations ranged from 1 ppm to 3 ppm.

Respirable Particulates (PM2,s)

Respirable particulate concentrations* indoors ranged between 9 pg/m^ to 14 pg/m- with an average 10 pg/m^- None of the indoor measurements for PM2.5 were above the NPAAQS of 65 pg/m3 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 such as asthmatic people and children. The outdoor respirable particulate concentrations ranged from 49 pg/m^ to 126 pg/m^ with an average of 71 pg/m^.

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

CITY_21MC100_003079936

NYC-WTC_000188391