NYC-WTC_000218435

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan February^ 4. 2002 Indoor Air Quality Assessment Page 3 P. S. 234M ATC Protect No. 15-19125-029^

Real-Time Environmental Measurements

ATC collected sixty (60) sets of real-time environmental measurements consisting of fifty (50) inside the school building and ten (10) outdoors. All tliree floors of the school were surveyed. Field data sheets are found in the Attachment. Readings began at 11:00 A.M. and concluded after 3:00 P.M. The results are described below.

Temperature

Indoor dry bulb temperature measurements ranged from 61.9 °F to 68.3 °F. Only two (2) measurements were within the range of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). The outdoor temperature range 44.0 to 50.8 °F.

Relative Humidity

The relative humidity indoors ranged from 33.0 percent to 45.2 percent. All measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity range was 43.9 to 47.6 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 512 ppm to 1202 ppm. .All COg measurements were below the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) COj concentration was 545 ppm. Therefore, the maximum acceptable level of COy at this location was 1245 ppm (background level + 700 ppm). Seven indoor locations had COy levels greater than 1000 ppm with few or no occupants. Tire highest reading (1202 ppm) was in Room 311 which had 10 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 COy indoors is occupant respiration. The school building during ATC’s assessment was not occupied.

Carbon Monoxide Concentration

Carbon monoxide concentrations indoors were 0-1 ppm for all readings. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentration range was 0-2 ppm.

Respirable Particulates (PM2_5)

Respirable particulate concentrations* indoors ranged between 19 pg/m^ to 60 pg/m^. All measurements were below the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter. Thirty-seven (37) were below the USEPA recommended concentration of 40 pg/m^ for sensitive individuals / children. The average PM2,5 concentration for the entire school building was approximately 35 pg/m^. The outdoor respirable particulate concentration range was 53 to 90 pg/m^.

CITY_21MC100_002878434

NYC-WTC_000218437