NYC-WTC_000214394

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan June 6, 2002 Indoor Air Quality Assessment Page 3 P. S. 150M_________________ _____________ ATC Project No. 15-19125-0289 t Real-Time Environmental Measurements

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

Field data sheets are found in Attachment 1. Readings began at l;09 P.M. and concluded at approximately 2:10 P.M.

Temperature

Indoor dry bulb temperature measurements ranged from 83.9 °F to 84.2 °F. Two (2) of the indoor measurements was above the range of 73 to 79°F (at 50 percent relative humidity) as recommended by the ASHRAE Standard 55-1992 during the mechanical cooling season (summertime conditions). The outdoor temperature measurements ranged from 83.9 °F to 84.2 °F.

Relative Humidity

The relative humidity indoors ranged from 41.4 to 53.7 percent. All of the measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. The outdoor relative humidity measurements ranged from 62.1 to 62.4 percent.

Carbon Dioxide Concentration

Carbon dioxide concentrations indoors ranged from 586 ppm to 1361 ppm. One (1) of the CO2 indoor measurements was above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The maximum outdoor (background) CO2 concentration was 590 ppm. Therefore, the maximum acceptable level of CO2 at this location was 1290 ppm (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. Hie school building was occupied during ATC’s assessment.

Carbon Monoxide Concentration

Carbon monoxide indoor concentrations ranged from 1 ppm to 2 ppm. These concentrations were below the NPAAQS/ASHRAE guideline of 9 ppm. The outdoor CO concentrations was 1 ppm for all collected readings.

Respirable Particulates (PM2^^ ppm.

Respirable particulate concentrations* indoors ranged between 10 pg/m^ to 21 pg/m^. None of the indoor measurements were above the NPAAQS of 65 pg/m^ 24-hour average concentration of particulate matter 2.5 micrometers or less in aerodynamic diameter or above the USEPA recommendation of 40pg/m^ for sensitive individuals and children. The average PM2.5 concentration for the entire school building was approximately 15 pg/m^. The outdoor respirable particulate concentration measurements ranged from 10 to 18 pg/m^ with an average of 15 pg/m^.

C11Y_21MC100_002810102

NYC-WTC_000214396