WHAT IS CONSIDERED AN "EFFECTIVE" AIR CLEANING DEVICE?

1. WHAT IS CONSIDERED AN "EFFECTIVE" AIR CLEANING DEVICE? - R Shaughnessy, PhD1 - R Sextro, PhD 1 Indoor Air Program, University of Tulsa, USA Email: rjstulsau@aol.com Ph: 918-230-3908 April ’06 JOEH

2. National Expenditures for IAQ Problem Prevention or Mitigation(LBNL – 58694, June 2005) • $15.9 billion annual business (range $12-20 billion) • Air clng and improved filtration………$1.5 billion • IAQ Consultant services……………….$2.1 billion • Building Remediation………………….$3.4 billion • Duct Cleaning…………………………..$ 4 billion • Asbestos/lead abatement……………….$ 4 billion • IAQ litigation/insurance………………..$500 million • Radon Mitigation……………………….$200 million • Certification/labeling……………………$100 million • Laboratory Services…………………….$100 million

3. Misleading Ads • “Removes virtually any contaminant including gases and VOCs” • “Relieves asthma and allergies” • “Eliminates allergies and other maladies caused by molds” • Eliminates almost 100% of such harmful airborne particulates as dust, bacteria, viruses, pollen, mold, spores, tobacco, and general room odors”

4. Dispelling Common Myths • Ozone Generators • Significant exposure to ozone and reaction byproducts • California DHS warning • FTC lawsuit • House Plants • Recirculating Range hoods • Desktop Air Cleaners

5. Particle Characteristics of Allergens SETTLING RATE Rapid (e g, 20 micron particle falls 1 meter in about 80 seconds) Fines settle slowly (e g, 0.2 micron particle falls 1 meter in about 5 days) Rapid Varies Rapid Negligible TYPE Dust Mite Cat/Pet Dander Cockroach Common Fungal Spores Plant Pollen ETS SIZE RANGE (micron) 10-35 <2 to >10 80% >10 2-10 15-25 Mean ~ 0.2 Particle must be airborne long enough for air cleaner to have any effect

6. Sizes of biological particles 1 micrometer Pollen House dust mite allergens Fungal spores Cat allergen Bacterial cells and spores Viruses

7. Historical Perspectiveon Portable Air Cleaners (1) Peshkin, M.N., and Beck, I. (1930), “New and Simplified Mechanical Air Filter in the Treatment of Hay Fever and Pollen”, J.Lab & Clin. Med. 15; 643. (2) Crisp, L.H., and Green, M.A., (1936), “Air Cleaning as Aid in Treatment of Hay Fever and Bronchial Asthma”, J. Allergy, 7: 120-138. (3) Kranz, P., (1963), “Indoor Air Cleaning for Allergy Purposes”, J. Allergy, 34:155. (4) Tuffley, R.E., and Zorab, P.A., (1964), “Portable Air Purifier”, Lancet, 41:415-6.* * Use of cellulose & asbestos blended filter for patients w/ bronchitis and asthma

8. Air Cleaning Technologies • Particle Removal • Filters • Electrostatic Precipitators (ESP) • Ionizers • Gas Removal • Adsorbents • PCO

9. Electrets • Polymeric extruded fibers with built-in charge • Advantages • Low pressure drop • Higher initial efficiencies due to inherent charge • Disadvatages • drop in efficiency during the loading life cycle once installed in an ambient airstream • VOCs or super-fine nanoparticles, can neutralize the fiber charge reverting the media to the lower efficiency levels of non-electret media

10. Owen, M.K., et al., 2003

11. Hanley, J., et al., IA ‘99

12. Electrostatic air cleaners(electronic, or electrostatic precipitators) • Basic design • Ionizing plate

13. Electronic air cleaners- ionizing plate Principle of operation

14. Electronic air cleaners • Advantages • High initial efficiencies; No pressure drop • Disadvantages • Produces ozone unintentionally • Requires frequent cleaning to maintain efficiency • EAC slowly loses its ability to charge particles due to build-up of silicone deposits on the electrical ionizing grid wires (Hanley, et al, 2003)

15. Ionizers • Rely on generation of - ions • Particles are charged and attracted to surfaces (plate-out/soiling) • Some configurations draw charged particles back to unit for collection • Poor performance historically • Ozone production • Concern over breathing charged particles

16. Portable Air Cleaners • 3 out of every 10 households now own P.A.C. • Effectiveness limited by flow rate and efficiency of collection • Primarily for cleaning air in a single room • Components must be replaced or cleaned periodically • Noise factors • Advertisements are inundated with hype • AHAM ratings for particle removal

17. Air Cleaner Led to Improvement in Health • One-third report that their use of an air cleaner has led to an improvement in their health / health of other household members. Base: Total returns (n=936). Source: Q50. Has use of an air cleaner led to an improvement in your health or the health of other household members?

18. Health benefits from Portable Air Cleaning • Studies far from definitive • Studies to date failed to separate effects of air clng from the effects of applied source control measures (i.e. allergen-proof bed encasings, washing pets, excl. pets from home, etc) • Well-designed studies needed; must include: • proper controls • clinical evaluation • rigorous control/reporting of relevant environmental variables(National Academy of Sciences, 2000, Eggleston, et al. 2001)

19. Type of Air Cleaner • Half own a HEPA filter air cleaner, while one fifth own a machine with an electrostatic filter or electrostatic precipitator. • One-quarter are not sure about the type of air cleaner they own. Base: Total returns (n=936). Source: Q20. What type of air cleaner do you own?

20. AHAM Standard AC-1, 2006 • AHAM testing of air cleaners in the U.S. • AHAM standards are presented to the American National Standards Institute (ANSI) for recognition as American National Standards • Testing for removal of particulate (smoke, dust, pollen) • Uses CADR model to evaluate performance of air cleaners • And from these figures calculate room size suitability (CADR x 1.5) Clean Air Delivery Rate (CADR) is the amount of “equivalent cleaned air” provided by an air cleaner

21. What is the minimum Effective Cleaning Rate, CADR, required to impact an indoor environment? • What is industry accepted value • What is reasonable • What is achievable • What does technology afford us • Strive for highest removal possible • International perspective

22. The AHAM recommendation for room size for a given CADR will result in an 80% reduction in ambient levels of particulates as the challenges vary throughout the day With and Without Air CleanerPollution vs. Time (Showing 80% Reduction)

23. Modeling the Indoor EnvironmentAssumptions: • air concentrations of contaminants well-mixed • change in contaminant conc’n described by 1st order differential equation

24. Mass Balance Equation: Where: S is the emission rate in mass per unit time V is the volume of the indoor space λν is the air infiltration rate (in units of inverse time) P is the penetration factor Co is the outdoor contaminant concentration Ci is the indoor contaminant concentration Λ represents all first order removal processes (in units of inverse time) (1) .

25. To be effective on contaminant removal, the air cleaner must compete with: • Surface deposition • Ventilation (outdoor air exchange) • With vapor-phase contaminants, rate of indoor rxns must be considered

26. Effectiveness, ε, has been defined by Nazaroff (2000) as the difference in indoor concentration due to air cleaning compared to the "no-cleaning" case; rearranging above equations ε can be expressed as: (7) . The closer the effectiveness is to 1, the more ideal the performance of the air cleaner is in removal of the contaminant

27. Figure 1. Effectiveness of airborne contaminant removal as a function of the ratio between air cleaner performance and the other removal processes, ventilation and deposition (for particles) (adapted from Nazaroff, et al., Healthy Buildings 2000)

28. Relationship between CADR, room size (ft2), (assuming 8 ft ceiling), 80 % removal (small particles)

29. Figure 2. Clean Air Delivery Rate as a function of indoor area for effectiveness value of 80% as recommended by AHAM; graph applies to removal of smaller particles, less than ~1 micron in size (Shaughnessy & Sextro, submitted, 2005).

30. Recall that: As λd increases, the effectiveness (ε) afforded by the air cleaner decreases

31. Figure 5. Particle removal by deposition as a function of particle size.”Small” refers to the particle size region associated with the peak in the ETS mass distribution; “medium” refers to the size region associated with some allergens and with larger ambient aerosols; and “large” refers to the size region associated with pollens & sources of asthma-related allergens such as dust mites. Thatcher, et.al. (2002) and Xu, et.al. (1994), as reported by Fisk, et.al. (2002)

32. Figure 3. Clean Air Delivery Rate as a function of indoor space area and particle size. Volume is based on a ceiling height of 8 ft. CADR-80, -67, and -50 are, respectively, the CADR values based on 80 %, 67% and 50% reduction in particle concentrations due to air cleaner operation. (Shaughnessy & Sextro, submitted, 2005).

33. NAS, Clearing the Air Report (2000):Limited evidence indicating that particle air cleaning is associated with a reduction in the exacerbation of asthma symptoms…. suggest that air cleaners are most likely to be effective in reducing indoor concentrations of particles smaller than 2 microns…. much of the airborne allergen appears to be within larger particles”

34. Selecting a Portable Air Cleaner • based on room size • noise factors • typically good for particulates only • not whole house • look for CADR of between 150-300 (AHAM rating); 80% effectiveness minimum for room size

35. Ozone Standards • EPA NAAQS: 80 ppb average over 8 hours • OSHA PEL: 100 ppb average over 8 hours (NIOSH IDLH = 5 ppm) • FDA: 50 ppb limit for medical devices

36. Ozone “Air Purifier” Ads • “thunderstorm in a box” • Greatly reduces pollutants such as: • MOLD MILDEW ODORS • BACTERIA FUMES DUST • POLLEN GASES CHEMICALS • SMOKE STALE AIR PET DANDER • FORMALDEHYDE SMOG GAS FUMES • “fresh as mountain air” • “provides relief from allergies & asthma” • “No harmful by products”

37. Shaughnessy and Weschler, (1999) “Growth of Submicron Particles as a Consequence of Ozone-Surface Reactions; Preliminary Data” Proceedings Indoor Air ‘99Weschler, C.J. and Shields, H. C. (1999) “Indoor Ozone/Terpene Reactions As a Source of Indoor Particles”, Atmospheric EnvironmentNazaroff and Weschler (2004)“Cleaning Products & Air Fresheners: Exposure to Primary and Secondary Pollutants”, Atmospheric EnvironmentIndoor Chemistry is Extremely Important…

38. Implications as to CADR CADR tests conducted on air cleaners that produce ozone (intentionally or unintentionally) in the absence of a terpene source do not capture particle generation phenomena and thus overstate CADR in the presence of such a source

39. Alpine Industries reportedly has sold more than 3 million units since 1987 ($1.2-1.6 billion retails sales) up until their litigation in 2001. (LBNL – 58694, June 2005)

40. EPA, 1998: “…ozone is generally ineffective in controlling indoor air pollution.” “The public is advised to use proven methods of controlling indoor air pollution.”

41. “Because of the documented negative health impact of ozone, especially for persons with asthma, and the lack of evidence for its ability, at low concentrations, to effectively ‘clean’ the air, the American Lung Association suggests that ozone generators not be used.”ALA ’97

42. Emerging Technologies • P.C.O. • UV-C • Sorbent technology • Ionization/electrostatic devices • Media filtration

43. Gas/vapor contaminants • Adsorption • Absorption • Catalytic oxidation/reduction • Botanical air cleaning (good luck) • Ozonation

44. Adsorption • Chemisorption • Nature of process • Media • Uses • e.g. activated alumina impregnated with potassium permanganate (HCHO oxidation)

45. Photocatalytic Oxidation (PCO) • Titanium dioxide (TiO2) is a semiconductor photocatalyst • UV light-driven catalytic oxidation of gas phase contaminants • Resultant oxidation of VOCs and degradation of bioaerosols

46. PCO Challenges • reaction rate inhibition due to humidity • mass transport issues associated with high-flow rate systems • formation of products of incomplete oxidation (primarily aldehydes) • catalyst deactivation and inorganic contamination (dust and soil).

47. UVGI Irradiation • used in TB isolation rooms, waiting rooms, radiology areas • duct or upper room irradiation mounts • CDC (1994) considers only as supplemental to engineering controls (i.e. ventilation, HEPA, negative P) • not demonstrated to be highly effective against fungal spores

48. Application of UV • upper room air irradiation • ductwork/plenum • portable air cleaners

49. "Effectiveness of Germicidal Ultraviolet Irradiation for Reducing Fungal Contaminants within Air Handling Units" Applied and Environmental Microbiology, Vol 67 #8, 3712-3715, August, 2001. Levetin, E., Shaughnessy, R.J., Rogers,C.

50. Summary • Positive correlation between operation of UV-C lamps and reduction of microbial growth in duct lining and drain pan samples from ahu s • Effect on bacteria in water more pronounced than on fungi • No ozone buildup noted Levetin, Shaughnessy, Rogers, 2001