NYC-WTC_000187673

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan March 20, 2002 Indoor Air Quality Assessment Page 3 P. S. 150M ATC Project No. 15-19125-0289

REAL-TlMK EN\ IRONMEN! AL MEASUREMENTS

ATC collected forty (40) sets of real-time environmental measurements consisting of thirty (30) from inside the school building and ten (10) from outdoors. Ail three floors of the school puilding were surveyed. These results are described below.

Held data sheets are found in Attachment 1. Readings began at 2:05 P.M. and concluded at approximately 3:30 P.M.

Tei^>er^tre

Indoor dry bulb temperature measurements ranged from 70.3°F to 74.0°F. All of the .neasiirements were within the range of 68 to 75°F (at 50 percent irelative humidity) as recommended by the ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature measurements ranged from 43.0 to 45.6°F.

Relative Humidity

rhe relative humidity indoors ranged from 28.0 to 32.3 percent. Sixteen (16) of the measurements were below the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. 1'hc outdoor relative humidity measurements ranged from 44.1 to 47.3 percent.

Carban Dioxide Coticentralion

Carbon dioxide concentrations indoors ranged from 409 ppm to 740 ppm. All of the (fOo measurements were within the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) cop concentration was 446 ppm. Therefore, the maximum acceptable level of CO2 at thi.s location was 1146 pprn (background level + 700 ppm). Levels above the recommended maximum do not indicate a health risk. Carbon dioxide measurements are used as an indicator of available outside makeup air. The primary source of CO2 indoors is occupant respiration. The school building was occupied during ATC’s assessment.

Carbon Monoxide Concentration

Carbon monoxide concentrations were 0 ppm for the interior readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentiation was also 0 ppm for all collected readings.

Respirable Particulates (PM2 M

Respirable particulate concentrations* indoors ranged between 8 pg/m^ to 25 pg/rn^. None of the indoor or outdoor measurements were above the NPAA(^S of 65 pg/m^- Three (3) of the outdoor measurements were above the USEPA recommendation of 40 pg/m^ for sensitive individuals and children. The average PM2.5 concentration for the entire school building was approximately 15 pg/m^. The PM2.5 average concentration was below the USEPA recommended concentration of 40 pg/m^ for sensitive individuals / children. The outdoor

CITY_21MC100_002954245

NYC-WTC_000187675