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

NYC 9/11 Public Portal Document

Oct-05-2001 11:04 From-CLAYTONGGROUPQ + T-624 P.007/021 F-261

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27 to 36 µg/m 3. The detection limit of the pDR instrument used to measure the respirable particulate concentrations was I pg/mz.

ASHRAE Standard 62-1999 recommends that levels of total particulate in outdoor air entering a building not exceed the USEPA's National Ambient Air Quality Standards (NAAQS) of 75 µg/ n 3_ Air containing higher levels of particulate must be filtered to bring particulate levels within the guidelines. ASHRAE Standard 62-1999 (Addendum to Ventilation for Acceptable Indoor Air Quality) recommends that, in accordance with the Clean Air Act of 1987 (i.e., tJSEPA's NAAQS), levels of respirable particulate (particles of less than 10 microns aerodynamic diameter) not exceed 50µg/rn3 in outdoor air entering a building.

All of the indoor airborne respirable particulate concentrations measured were less than 50µg/m3.

Carbon Dioxide

Carbon dioxide concentrations measured by Clayton indoors in the building ranged from 420 to 680 parts per million of air (ppm). The outdoor carbon dioxide concentration ranged from 410 to 450 ppm over the 3-day evaluation. The accuracy of the direct-reading instrument used by Clayton is ± 50 ppm.

ASHRAE Standard 62-1999 recommends indoor carbon dioxide concentration of not more than 700 ppm above the outdoor carbon dioxide concentration. Based upon the outdoor levels measured over the 3-day evaluation, the recommended upper limit for indoor carbon dioxide concentrations within the building would be calculated as approximately 1,110 to 1,150 ppm. As such, the interior carbon dioxide concentrations measured by Clayton were less than the ASHRAE Standard 62-1999 upper limit, thereby suggesting an adequate supply of outdoor air to the building.

Carbon dioxide is a product of human respiration and a surrogate for various occupant-generated indoor contaminants. Carbon dioxide does not present a health hazard at these relatively low levels; however, concentrations which exceed the ASHRAE Standard 62-1999 upper limit generally are indicative of insufficient outdoor air ventilation (i.e., outdoor airflows below 15 cubic feet per minute [cfm] per occupant), The OSHA PEL for carbon dioxide exposure is 5,000 ppm as an 8-hour time-weighted average (TWA).

Carbon Monoxide

Carbon monoxide was not detected above I ppm at any of the indoor measurement locations. Likewise, carbon monoxide was consistently measured at I ppm at the Wall Street outdoor sampling location. The accuracy of the direct-reading instrument used by Clayton is ±3 ppm -

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