Asbestos air quality report cover letter, 14 Wall Street, Oct

NYC 9/11 Public Portal Document

Oct-05-2001 11:04 From-CLAYTONGGROUPQ + T-824 P.008/021 F-281

` C LI.UP esyton

Carbon monoxide is a colorless, odorless gas produced -by.the,incemplele combustion of solid, liquid, and gaseous fuels. In the absence of indoor sources, indoor carbon monoxide concentrations are generally similar to outdoor concentrations. ASHRAE Standard 62-1999 recommends an upper limit for carbon.monoxide of 9 ppm as an 8-hour average, and 35 ppm as a 1-hour average. The OSHA PEL for carbon monoxide exposure is 50 ppm as an 8-hour TWA.

L!iy Bulb Temperatures The outdoor range of air temperatures over the 3-day evaluation, as measured on Wall Street, was 71 to 75 °F. Dry-bulb temperatures measured within the building ranged from 67 to 78 OF, with one exception. The temperature in the mechanical area of subgrade level E was 76 to 82 °F.

ASHRAE Standard 55-I992 recommends indoor summer-season temperature lower and upper limits for occupant comfort of approximately 73.0 °F and 79.0 °F (when indoor relative humidities are approximately 50 percent). As such, the temperature ranges measured within the building were within the ASHRAE Standard 55-1992 upper and lower limits for comfort.

Relative Humidity

Indoor relative humidity ranged from 42 to 57 percent. The outdoor relative humidity level over the 3-day evaluation ranged from 67 to 76 percent. Clayton regards the broad range of indoor relative humidity of 30 to 60 percent as the most acceptable for occupant comfort. As such, relative humidity levels measured within the building were determined to be within these acceptable ranges.

Indoor relative humidity levels above 60 percent can promote indoor microbial growth. Wintertime relative humidity levels in the 20 to 30 percent range are marginally acceptable, but may cause discomfort to sensitive individuals. Humidity below 20 percent is less acceptable because of the effect of dry air on both the mucous membranes and the skin_

3.2 AIRBORNE FIBER CONCENTRATIONS

Clayton collected one area air sample for airborne fiber concentrations per floor evaluated. Generally, the air samples were collected in proximity to the main elevator lobby of each floor. Bankers Trust occupies floors 2 through 7, Mezzanine Two, and subgrade levels A and C. Sampling locations on these floors were determined by a Bankers Trust building engineer.

The sampling and analysis protocol for the collection of area air samples for airborne fibers was conducted in accordance with NIOSH Method 7400, A Rules. Samples were collected using 25-millimeter (mm) 0.8-micron (pm) mixed cellulose ester filters (MCEF) and high-volume air sampling pumps calibrated with a flowrate of approximately 13 liters per minute. A minimum volume of approximately I ,200 liters of air was collected for

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