NYC-WTC_000207834

NYC 9/11 Public Portal Document

00/30/2002 08:20 FAI 212 353 8306 ATC 1^023

Mr. Bernard P. Orlan September 30 2002 Indoor Air Quality Assessment Page 3 P- S, 65Q ATC Project No. 15-19125.0334

Relative Humidity

The relative humidity indoors ranged from 55.3 percent to 74.8 percent Sixty-one (61) of the indoor measurements for relative humidity were above the A$HKAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 61.6 to 76.3 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 441 ppm to 1005 ppm. All of the indoor measurements were within the ASHRAE Standard 62-2001 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 583 ppm. Therefore, the maximuni acceptable level of CO2 at this location was 1283 ppm (background level -1- 700 ppm). The highest reading (1042 ppm) was recorded in Room 1 approximately at 11:30 A.M. with 30 occupants. 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 ranged from 1 ppm to 2 ppm for all readings. These concentrations were within die NPAAQS/ASHRAE guideline Of 9 ppm. The outdoor CO concentrations also ranged from I ppm to 2 ppm.

OBSERVATIONS

During this assessment, ATC noted the following:

• The building was occupied at the time of tire assessment; • No unusual odors were detected.

FINPINGS

Based on the real-time measurements, the following findings are presented:

1. Ninety-nine (99) of the indoor temperature measurements were below the range of 73 to 79°F (at 50 percent relative humidity) as recommended by ASHRAE Standard 55-1992 during the mechanical cooling season (summertime conditions). 2. Sixty-onc (61) of the indoor measurements for relative humidity were above the ASHRAE- recotilmended range of 30 to 60 percent for occupant comfort. 3. All of the indoor CO2 measurements were within the ASHRAE Standard 62-2001 recommended maximum concentration of <700 ppm above the background level. 4, Concentrations of CO ware within applicable guidelines.

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NYC-WTC_000207836