Collection of Biological and Non-Biological Particles by New and Used Filters Made from Glass and Electrostatically Charged Synthetic Fibers

Details

• Personal Author:
  Horns JH ; Kim BG ; Ramachandran G ; Raynor PC ; Streifel AJ ; Strommen MR
• Description:
  Synthetic filters made from fibers carrying electrostatic charges and fiberglass filters that do not carry electrostatic charges are both utilized commonly in heating, ventilating, and air-conditioning (HVAC) systems. The pressure drop and efficiency of a bank of fiberglass filters and a bank of electrostatically charged synthetic filters were measured repeatedly for 13 weeks in operating HVAC systems at a hospital. Additionally, the efficiency with which new and used fiberglass and synthetic filters collected culturable biological particles was measured in a test apparatus. Pressure drop measurements adjusted to equivalent flows indicated that the synthetic filters operated with a pressure drop less than half that of the fiberglass filters throughout the test. When measured using total ambient particles, synthetic filter efficiency decreased during the test period for all particle diameters. For particles 0.7-1.0 mum in diameter, efficiency decreased from 92% to 44%. It is hypothesized that this reduction in collection efficiency may be due to charge shielding. Efficiency did not change significantly for the fiberglass filters during the test period. However, when measured using culturable biological particles in the ambient air, efficiency was essentially the same for new filters and filters used for 13 weeks in the hospital for both the synthetic and fiberglass filters. It is hypothesized that the lack of efficiency reduction for culturable particles may be due to their having higher charge than non-biological particles, allowing them to overcome the effects of charge shielding. The type of particles requiring capture may be an important consideration when comparing the relative performance of electrostatically charged synthetic and fiberglass filters. PRACTICAL IMPLICATIONS: Electrostatically charged synthetic filters with high initial efficiency can frequently replace traditional fiberglass filters with lower efficiency in HVAC systems because properly designed synthetic filters offer less resistance to air flow. Although the efficiency of charged synthetic filters at collecting non-biological particles declined substantially with use, the efficiency of these filters at collecting biological particles remained steady. These findings suggest that the merits of electrostatically charged synthetic HVAC filters relative to fiberglass filters may be more pronounced if collection of biological particles is of primary concern. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Conditioning Air Pollutants, Occupational Dust Environmental Monitoring Hazardous Substances Inhalation Exposure Microbiology Occupational Health Particulate Matter Respiratory System Safety Ventilation

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• Keywords:
  Aerosol-particles Air-conditioning Air-conditioning-equipment Air-quality-measurement Airborne-dusts Airborne-particles Author Keywords: Air Filters Biohazards Biological-effects Dust-measurement Dust-velocity Efficiency Electret Electrostatic-filters Exposure-assessment Exposure-levels Exposure-methods Filter-fabrics Filter-materials Heating Ventilating And Air-conditioning Inhalants Inhalation-studies Magnetic-properties Mathematical-models Microorganisms Microscopy Particle-aerodynamics Particle-counters Particulate-dust Particulates Physiological-effects Pressure-testing Quantitative-analysis Standards Statistical-analysis Ventilation-systems

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• ISSN:
  0905-6947
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Minnesota ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  51-62
• Volume:
  18
• Issue:
  1
• NIOSHTIC Number:
  nn:20037441
• Citation:
  Indoor Air 2008 Feb; 18(1):51-62
• Contact Point Address:
  Peter C. Raynor, University of Minnesota, School of Public Health, Division of Environmental and Occupational Health, Mayo Mail Code 807, 420 Delaware St. SE, Minneapolis, MN 55455
• Email:
  praynor@umn.edu
• Federal Fiscal Year:
  2008
• Performing Organization:
  University of Minnesota Twin Cities
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Indoor Air
• End Date:
  20250630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f5def60df2170176b63b1be06a52821977d85289b0aaf5745e665666e81fb07971755382af35d7e6c0f5d87a255eed89938a1ccb02fd8b5af9a1374bcfbc1335
• Download URL:
  https://stacks.cdc.gov/view/cdc/188537/cdc_188537_DS1.pdf
• File Type:
  [PDF - 424.03 KB ]