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In-depth survey report: evaluation of general exhaust ventilation system at Internal Revenue Service Service Center Fresno, California.

Beamer BR; Guishard C; Marlow D
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 278-11a, 2004 Aug; :1-23
As a result of an evaluation by National Institute for Occupational Safety and Health (NIOSH), researchers of the general exhaust ventilation system for negative-pressure rooms at the Internal Revenue Service (IRS) Service Center in Fresno, California, the following recommendations are made: 1. Recommendations for Non-Working hours - Using the information in Table 4, the IRS should be able to determine how long to run existing HVAC systems during off-hours to both mitigate the effects of a possible contaminant release and save money on energy costs. For instance, to decrease contaminant by about 99%: a) the system should run for approximately 1.3 hours in the Extracting Room; b) the system should run for approximately 52 hours in SCAMPS I; and c) the system should run for approximately 19.6 hours in SCAMPS II. 2. Local Exhaust Ventilation - In order to maximize the effectiveness of ventilation systems to protect workers from acts of bioterrorism, the IRS should consider using local exhaust ventilation (LEV) as part of an overall ventilation system in the SCAMPS areas. The benefits of such a system would be that: a) the air currents at the point of contamination would draw contaminant away from SCAMPS room workers, providing them with much more protection than is currently employed; b) by capturing the contaminant close to the source, much lower air flows are needed to cover the area of contamination. This would result in lower costs for air handling and treatment of make-up air; and c) the general air flows in the rooms would be more protective of workers by moving "clean" air from areas of the room where contaminant is not likely to be released past workers and to the LEV. 3. Maintaining Negative Pressure - Tracer gas experiments showed that tracer gas escapes from SCAMPS II to "positive-pressure" areas of the building when the doors are opening and closing. In order to better meet minimum requirements, the IRS should consider installing an exhaust system into SCAMPS II in order to keep this room under negative pressure when doors are opening and closing. 4. Supply Air into the SC4MPS Room - Neither SCAMPS I nor SCAMPS II currently employs fresh supply air as part of its ventilation system Introducing fresh supply air would accomplish several objectives: a) any contaminant released in these rooms would be diluted more quickly, better protecting the health of SCAMPS room inhabitants in the case of a bioterrorist attack; b) by bringing in fresh supply air, the variable flow drives (VFD) in SCAMPS II would engage more frequently because of the resultant pressure differential (currently set for .01 "wg). This would result in faster contaminant decay and would allow IRS facilities personnel to turn off HVAC systems in these rooms during off hours sooner; and c) introducing fresh air into these rooms would help the IRS meet Indoor Air Quality guidelines. 5. Other Recommendations - The following are other recommendations made based on the results of the survey that the IRS should consider: a) the filtration component of the Computer Room Air Conditioning (CRAG units in SCAMPS I should not be considered adequate to filter biologically contaminated air; b) in order to save money, the IRS might consider re-entraining exhaust air from the Extracting Room and SCAMPS rooms back into the facility after passing through a high efficiency particulate air (HEPA) filtration system; and c) if, however, IRS facilities personnel determine that exhaust air should not be re-entrained into the facility, but rather exhausted to the atmosphere, the air can either be unfiltered or pass through a lower efficiency air filter like a MERV-14 or MERV-16
Ventilation; Ventilation-equipment; Ventilation-systems; Environmental-control-equipment; Exhaust-systems; Exhaust-ventilation; Control-technology; Air-quality-control; Biological-weapons; Region-9
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Mail Stop R-5, 4676 Columbia Parkway, Cincinnati, OH 45226-1998
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Field Studies; Control Technology
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National Institute for Occupational Safety and Health
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division