NYC-WTC_000179059

NYC 9/11 Public Portal Document

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Indoor dry bulb temperature measurements ranged from 68.7 °F to 75.5 °F. Only one (I) measurement was above the range .of 68 to 75°F (at 50 percent relative humidity) recommended by ASHRAE Standard 55-1992 during the heating season (wintertime conditions). This measurement was collected from room 23 I. The outdoor temperature range was 36.9 to 38.5 °F.

Relciiive Humidiiv

The relative humidity indoors ranged from 22.1 percent to 33.7 percent.. Only sixteen (16) measurements were within the ASHRAE-recommended range of 30 to 60 percent for occupant comfort. All other measurements were below the ASHRAE-recommended range. The outdoor relative humidity range was 26.9 and 32.1 percent.

Carbon Dioxide Concentrcil.ion

Carbon dioxide concentrations indoors ranged from 569 ppm to 1824 ppm. Eighteen (18) COo measurements were above the ASHRAE Standard 62-1999 recommended maximum concentration of <700 ppm above the background level. The outdoor (background) COn concentrations were 445 ppm and 468 ppm. Therefore, the maximum acceptable level of COn at this location was 1168 ppm (background level + 700 ppm). The highest reading, 1824 ppm, was in Room 738. Rooms with COo levels above the recommended maximum were found on 3'*^, 4fl\ 5*^1'’, 7^''’, 9^1'' and 10**'* floors. 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 COn indoors is occupant respiration.

Carbon Monoxide Concenlixjtion

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

Rexpiruble Parliciilal.es fPMi, .

Respirable particulate concentrations* indoors ranged between 8 pg/m^ to 30 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. The outdoor respirable particulate concentrations were 15 and 32 pg/m^.

Filters with a higher efficiency rating were installed on the HVAC units that serve rooms on the 3''^. 6^1'* and 7^*'' floors (See Attachment 1). The PM2.5 concentration range for those rooms- was 11-23 pg/mJ with an average of approximately 18 pg/m^. The PMa j concentration range for the other.rooms was 8 - 30 pg/m-’ with an average of approximately 14 pg/m-’. The average PMt 5 concentration for the entire school building was approximately 15 pg/m-’. In addition to higher efficiency rating filters on their HVAC units, portable High Efficiency Particulate Air (HEPA) purifiers were, placed in Rooms 327. 333. 638 and 740. The PMo j concentration range for these rooms was 9 - 35 pg/m-’ with an average of approximately 22 pg/m^.

CONFIDENTIAL, CITY_21MC100_003457522 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

NYC-WTC_000179061