NYC-WTC_000234853

NYC 9/11 Public Portal Document

Ventilation, Air Monitoring and Thermal comfort

The area is served by an air conditioning/ventilation (AC) unit located on the same floor. The mechanical room was inspected on February 14, 2001. It was found to be in good condition with the air filters in good shape. The type of filters used were of the pleated type medium efficiency filters as recommended by EPA/ NIOSH. The unit was in operation, and the outside air dampers were open. The cooling coils were clean, no rust under coils was observed. Ventilation to the offices is provided through ducts and ceiling diffusers. Approximately first 30 feet of duct after the AC unit is lined with fiberglass insulation as per NYC Building Code. It is done in order to reduce the transmission of noise from AC unit through the duct system. Thermal insulation consist of fiberglass covered with acrylic coating to prevent insulation erosion. We visually observed the condition of the internal duct insulation by opening the duct access door. Insulation was found to be in a good shape. The subsequent office and file room air sampling for fiberglass revealed that levels of fiberglass were well below NIOSH REE (see attached Technical report). Total dust air sampling was done in the office area and in the file room. Total dust levels were well below OSHA PEL. The sampling media for dust and fiberglass was analyzed by Free- Col Laboratories, which accredited by American Industrial Hygiene Association.

The carbon monoxide levels were in the range of 0 to 1 parts per million (ppm), which is well below both the OSHA PEL and NAAQS of 50 ppm and 9 ppm accordingly. Formaldehyde was not detected. Carbon dioxide (CO2) levels were in the range of 525-550 parts per million, below the ASHRAE recommended maximum of 1000 ppm (ASHRAE Standard 62-1989 “ Ventilation for Acceptable Indoor Air Quality”.) CO2 levels below 1000 ppm indicating adequate ventilation rate. Since carbon dioxide is given off by humans when exhaling, its level in the air provides an indication on how effective the ventilation system is diluting and removing contaminants from the air. All air vents were in operation. Air velocities measured were in range of 150 - 300 feet per minute.

The temperature on the day of the survey was in the range of 74-75° F and 23-24% respectively, within the ASHRAE guidelines. Relative humidity was 23-24%, slightly below ASHRAE guidelines of 30%. However, employees stated that the office thermometer indicated that on certain days in the winter time the temperature varied between 85-90 °F and the relative humidity was down to 10-15%. If in the winter time temperatures are maintained at the lower end of the comfort range (70-73° F), the relative humidity will not fall much below 30%. RH levels below 20% are associated with increased discomfort, drying of mucous membranes, eye irritation and the frequency of colds.

It was observed that the temperature sensor was not functioning properly. The sensor failed to shut the perimeter radiators off when the room temperature reached above 73° F. According to your information, the sensor was later fixed by building maintenance. It should be noted that part of the office area is faced South, so on a sunny day, when the temperature sensor failed, the temperature may go up to 90" F.

2

CITY_21MC100_006267836

NYC-WTC_000234854