NYC-WTC_000202327

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan May 13, 2002 Indoor Air Quality Assessment Page 3 P. S. 89M ATC Project No. 15-19125-0297

Real-Time Ewvikonmemal Measurements

ATC collected eighty (80) sets of real-time environmental measurements consisting of seventy- one (71) from inside the school building and nine (9) from outdoors. All five floors of the school building were surveyed. These results are described below.

Field data sheets are found in Attachment 1. Readings began at 8:00 A.M. and concluded at approximately 11:30 A.M.

Temperature

Indoor dry bulb temperature measurements ranged from 70 °F to 76 °F. Fifteen (15) of the indoor measurements for temperature were below the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the summer season . The outdoor temperature measurements ranged from 68.3°F to 69.9 °F.

Relative Humidity

The relative humidity indoors ranged from 44.8 to 54.3 percent. All 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 53 to 55.5 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 702 ppm to 1874 ppm. Five (5) of the indoor measurements for CO2 were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 661 ppm. Therefore, the maximurh acceptable level of COq at this location was 1361 ppm (background level + 700 ppm). The highest reading was measured in room 404 at 10:00 AM with 29 occupants. 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 indoors ranged from 1 ppm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration was 1 ppm for all collected readings.

Respirable Particulates (PM,

Respirable particulate concentrations* indoors ranged between 20 pg/m’ to 50 pg/m’. The average PM2.5 concentration for the entire school building was approximately 33 pg/m-*. All of the indoor measurements were below the NPAAQS of 65 pg/m’ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Ten (10) of the seventy-one (71) instantaneous indoor readings were above the USEPA recommended concentration of 40 pg/m’ for sensitive individuals and children. The outdoor respirable particulate concentration measurements ranged from 90 to 100 pg/m’ with an average of 95 pg/m\

CITY_21MC100_003271995

NYC-WTC_000202329