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Particles & Filtration; Healthcare Construction Certification
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Particles & Filtration; Healthcare Construction Certification

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One of several presentations developed for the Healthcare Construction Certification Program.

One of several presentations developed for the Healthcare Construction Certification Program.

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  • WHEA Chapter VI May 16, 2007 © 2007 Michaels Engineering Inc.
  • WHEA Chapter VI May 16, 2007 © 2007 Michaels Engineering Inc.

Particles & Filtration; Healthcare Construction Certification Presentation Transcript

  • 1. Particulate Matter and Filtration in Healthcare Presented by: Wane A. Baker, P.E., CIH Division Manager, Indoor Air Quality MICHAELS ENGINEERING INC. Email: wab@MichaelsEngineering.com 608/785-1900 Healthcare Construction Certification Program
  • 2.
    • AGENDA
    • What is particulate matter?
      • Definitions
      • Health effects
    • Controlling particulate levels
      • Four mechanisms of filtration
      • Rating systems
      • Filter selection in healthcare
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 3.
    • Definitions
    • Aerosols : airborne solid and liquid particles
    • Size expressed in microns = micrometers ( µm )
      • “ Aerodynamic diameter ” = same behavior in air as a spherical particle of unit density
      • For particles of aerodynamic diameter less than 0.5 μm, the “ particle diffusion diameter ” should be used instead
    • Size range: generally from 0.005 – 100 microns
    • Comparisons
      • diameter human hair: 60-70 microns
      • smallest visible: 20-30 microns
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 4. Particulate Matter and Filtration
  • 5.
    • Definitions (cont’)
    • Particulate matter: ‘ fine’ solid or liquid particles
      • Generally, less than 30 µm
    • Composed of dust, smoke, fume, mist, fibers
    • EPA vs. industrial hygiene classifications
    • Total particulate, PM 10 , PM 2.5
      • Coarse, fine, ultrafine
      • Inhalable, thoracic, respirable
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 6. Particulate Matter and Filtration
    • Sources include mechanical reduction (grinding), wind erosion, combustion (wildfires, I.C. engines, boilers), skin flakes, paper dust, insect parts, natural and synthetic fibers, industrial processes, smog, copiers and printers
      • People emit large numbers of particles:
        • 400,000 per minute sitting at a desk
        • 45,000,000 per minute during exercise
    • Fine and ultra-fine can be reduced by avoiding vehicle emissions and other combustion devices, source capture at printers, copiers
      • A portion of UFP may pass through HEPA filters
      • Diffusion a function of velocity [later section…]
    Healthcare Construction Certification Program © 2007 Michaels Engineering Inc.
  • 7.  
  • 8.
    • Definitions (cont’)
    • Inhalable: <100 μm
      • the mass fraction inhaled through the nose and mouth
      • Particles larger than 30 μm unlikely to enter nasal passages
    • Thoracic: <10 μm (PM 10 )
      • the mass fraction penetrating beyond the larynx
    • Respirable: <2.5 μm (PM 2.5 )
      • the mass fraction penetrating to the unciliated airways
      • IH definition: < 4.0 microns (d 50 cut-point)
    • Ultrafine particles (UFP): <0.1 micron
      • 0.1 micron = 100 nm (“ nano particles ”)
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 9.  
  • 10.  
  • 11.
    • Health effects
    • Allergies, asthma, bronchitis, HP, COPD, pneumoconiosis, carcinogens, metal fume fever, infections, systemic toxicants
    • A statistically significant increase in morbidity and mortality associated with fine PM in ambient air
      • Mean increase in death rate from cardiovascular and respiratory causes was found to be 0.68% for each 10  g/m 3 increase in PM 10
      • ( New England Journal of Medicine , Vol 343, No 24, Dec. 14, 2000)
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 12.
    • Health effects (cont’)
    • Particle surfaces adsorb VOCs, oxidants
    • Effective at delivering organics, toxics to lung tissues
    • UFP believed to overwhelm cleaning mechanism in alveoli, damage epithelial cells, cause inflammation
      • Increases potential for bronchitis, asthma
    • Diesel particulate: an area of intense research effort
      • e.g., “Health Assessment Document for Diesel Engine Exhaust”, EPA/600/8-90/057F, May 2002
    • In healthcare, bioaerosols are a specific concern
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 13.
    • Controlling particulate levels
      • Avoid generating them; source control
      • Physical separations and pressure differentials between sources and sensitive populations
        • Can be very effective
        • Must be monitored, recorded
      • Filtration
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 14.
    • Filtration
      • A filter is not (just) a screen or a sieve!
      • Particulate removal by four mechanisms
        • Sieving / Straining
        • Impingement / Inertial impaction
          • Particles > 0.5 µm; a function of velocity, fiber size
        • Interception
          • Particles > 0.5 µm; relatively insensitive to velocity
        • Diffusion
          • Particles < 0.2 µm; sensitive to velocity
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 15.  
  • 16. (Sieving) (Inertial)
  • 17.
    • Filtration (cont’)
      • Diffusion (cont’)
        • Kinetic theory of gases  Brownian motion
        • At room temperature, average speed of gas molecules is ~500 m/s (100,000 ft/min; 1120 mph)
        • But there are ~ 10 12 collisions per second
        • Net result: movement of about 1 cm per second
      • Also electrostatic forces
      • Viscous impingement coatings
        • Reduce particle bounce, subsequent release
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 18.  
  • 19.
    • Rating air filters
      • Arrestance
        • Mass of standard test dust removed
      • Atmospheric dust spot efficiency
      • Minimum efficiency reporting value
      • HEPA
        • High-efficiency particulate air
      • ULPA
        • Ultra-low-penetration air
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 20. Particulate Matter and Filtration
  • 21.
    • ASHRAE Std 52.1
      • Arrestance – ‘nuff said
      • ADSE (Atmospheric dust spot efficiency)
      • Essentially measures ability to reduce soiling
      • Based on light transmission through spot of dust on HEPA filter paper
      • Uses ambient particulate; soot discolors filter
      • Relatively independent of local aerosol
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 22. Particulate Matter and Filtration
  • 23.
    • ASHRAE Std 52.2
      • MERV (Minimum efficiency reporting value)
      • Tests filters over 12 particle size ranges, from 0.3 µm to 10 µm
      • Test aerosol is potassium chloride (KCl)
      • Successive loading with SAE Arizona road dust, carbon black, cotton linters
      • Based on minimum efficiency at each size range in six loading curves
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 24.  
  • 25. IEST: Institute of Environmental Sciences and Technology
  • 26.
    • HEPA: high-efficiency particulate air
      • Developed >50 years ago for control of radioactive particles during the Manhattan project
      • Definition: 99.97% at 0.3 µm
      • Institute of Environmental Sciences (IES) definition:
        • &quot;a throw-away extended-media dry-type filter in a rigid frame, having minimum particle-collection efficiency of 99.97% for 0.3 µm thermally-generated dioctyl phthalate (DOP) particles … and a maximum clean-filter pressure drop of ... 1.0 in w.g. when tested at rated air flow capacity.&quot;
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 27.
    • ULPA: ultra-low-penetration air
      • Definition: 99.999% efficient at the “most-penetrating particle size” and at the specified media velocity.
      • Previous work had calculated that the most-penetrating size particle for a HEPA filter was 0.3 µm
      • Development of the laser photometer dust particle counter provided evidence that the most-penetrating size is less than 0.3 µm , and depends not only on the filter media but also on the velocity of air through it.
    © 2007 Michaels Engineering Inc. Particulate Matter and Filtration Healthcare Construction Certification Program
  • 28. Particulate Matter and Filtration
    • Filter Selection in Healthcare
      • Sources of guidance/requirements
      • 2006 AIA “Guidelines for Design and Construction of Health Care Facilities”
      • ASHRAE/ASHE Proposed Standard 170P: “Ventilation for Health Care Facilities”
        • 45-day Public Review from September 22, 2006 to November 6, 2006
    © 2007 Michaels Engineering Inc.
  • 29.  
  • 30.  
  • 31.  
  • 32.  
  • 33. Particulate Matter and Filtration
  • 34.  
  • 35. Particulate Matter and Filtration Thank you! Wane A. Baker, P.E., CIH Division Manager, Indoor Air Quality Michaels Engineering Inc. 608/785-1900 Email: [email_address] Website: www.MichaelsEngineering.com Questions? © 2007 Michaels Engineering Inc.