SAFHE/CEASA 2011 - Airborne disinfection methods

a : R review of airborne disinfection X V A n research and techniques Presented by Peta de Jager for the architectural engineering research group CSIR Built Environment unit 2011 SAFHE CEASA conference OR Tambo Conference Centre, BirchwoodSlide April 71 2011

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Introduction Mechanics of transmission Considerations Techniques Dilution Filtration UV 1: Zonal UVGI UV2: In-duct UVGI UV 3: Recirculation Photocatalytic Oxidation Plasmacluster Ions Advanced distribution Riley Wells experimental TB ward, Baltimore 1958-62: Source Nardell 2010 References Disinfect tr.v. To cleanse of disease carrying micro-organisms Disinfectant n. An agent that disinfects by destroying, neutralising, or A review of airborne inhibiting the growth of disease carrying organisms

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Airborne pathogens • Bacteria – Measles – Tuberculosis – Varicella • Bacterial spores • Viruses – Influenza A – Picornavirus – Adenovirus Riley Wells experimental TB ward, Baltimore 1958-62: – Coronavirus (SARS) Source Nardell 2010 Fungal spores A review of airborne •

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Mechanics of transmission Infectious particles <10 µm can penetrate the lungs Evaporation can halve coughed particle size Tang and Settles Schlieren photography http://www.multimedia.kolobrzeg.pl/tag/th-image/ A review of airborne experimental difficulties in working with bio aerosols include:

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Mechanics of transmission • For transmission to occur environmental factors must be conducive to pathogen survival – Temperature, relative humidity (RH) • Effect on relative humidity on pathogenic bacteria scarce – Some data on non-pathogenic surrogates • 40 – 60% RH less favourable to non-pathogenic bacteria [Hatch, et al] • High RH less favourable for high-lipid viruses • High RH more favourable for viruses with no lipid [Assar , et al] A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Mechanics of transmission RH experiment influenza A with guinea pigs in a chamber [Lowen, et al] – Temperature 20˚ RH 20 % RH 35 % RH 65 % A review of airborne RH 80 %

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Considerations Is the technology • effective, • non-harmful, • useful, – cost effective – compatible with existing circumstance (for example ergonomics of retrofitting), and • user-friendly – should not undermine comfort conditions – easy to maintain – – A review of airborne acceptable noise levels energy efficient

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Techniques • Air dilution • Filtration • Ultraviolet germicidal irradiation (UVGI) – Zonal (upper air or lower room) – In-duct – Recirculation • Photocatalytic oxidation • Plasmacluster ions • Electrostatic precipitation • Ozone generators • A review of airborne Advanced air distribution techniques – Personalised ventilation

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Techniques: Plasmacluster ion, alpha electrolytic Plasmacluster ion technology. Claims to: • neutralize 26 kinds of harmful airborne substances • use negative (O2 -) and positive (H+) ions inactivate the pathogen by binding on their surfaces, change the structure of the proteins/polysaccharides by stealing an OH-radical, changing the properties of the pathogen rendering it “impotent” Possible elevated levels of ozone alpha electrolytic water disinfectant system A review of airborne http://www.csnstores.com/Sharp Source - http://www.engadget.com/

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Techniques A review of airborne Source: http://www.scripps.edu/news/scientificreports/ Source: http://www.uvcomparison.com/uvscience.php

1835 Wheatstone invents mercury vapor arc lamp Hockberger 20021850 Stokes invents quartz arc lamp that produces 185 nm Hockberger 20021842 Becquerel and Draper find 340-400nm light photoreactive Hockberger 20021877 Bactericidal effects of sunlight demonstrated Downs and Blunt1889 UV light demonstrated to be erythemal Widmark1892 UV component of sunlight identified as biocidal Ward1892 Geissler demonstrates arc lamps lethal to typhosus B. Hockberger 20021903 UV spectrum from 226 to 328nm found to be germicidal Barnard and Morgan1904 First quartz lamp for UV developed Lorch 19871906 UV used to disinfect drinking water van Recklinghausen 19141921 UV photoreactivity with TiO demonstrated 2 Renz1925 UV photodegradation of materials demonstrated Luckiesh and Taylor1927 Erythemal action spectrum published Hausser and Vahle1927 Bactericidal action scientifically quantified Bedford and Gates1928 Virucidal action scientifically quantified Rivers and Gates1929 Fungicidal action scientifically quantified Fulton and Coblentz1932 UV germicidal peak at 253.7nm isolated Ehrismann and Noethling1932 Erythemal action spectrum quantified Coblentz et al.1936 Overhead UV system in hospitals Wells and Wells, Hart1936 UV photoreactivation phenomena identified Prat1937 Upper air UV to schools Wells1938 Fluorescent gas discharge UV lamp Whitby and Scheible 20041940 UV to airconditioning systems Rentschler and Nagy1942 UV air disinfection sizing guidelines Luckiesh and Holladay1950 First catalogue sizing methods (General Electric) Buttolph and Haynes1954 UV reduce micro-organisms impingement on AHU Harstad et al.1954 UV is ineffective (faulty study) MRC1957 UV is effective for TB Riley A review of airborne1959 Microbes on cooling equipment causes respiratory infection Anderson1974 Microbial growth control systems Grun and Pitz1985 Cooling coil UVGI (European Breweries) Philips1997 UV LEDs at 265nm Guha and Bojarczuk2003 In-duct UVGI demonstrated to reduce illness symptoms Menzies et al .

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES: Upper Air UV1 Riley-Middlebrook, 1976 - aerosolized BCG Exposure chamber, interior, Anderson air sampling equipment, aerosol generator A review of airborne Riley 1976: Source Nardell 2010

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES: UV Riley-Middlebrook, 1976 - aerosolized BCG • Room scale-study • Single unshielded 17 W UV lamp • Unventilated room • Air mixing by radiator Established current guideline of : 30 W fixture per 18,59m2 area. A review of airborne Riley 1976: Source Nardell 2010

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Determination of UV susceptibility of various airborne organisms Z value The Z-value represents the ratio of the inactivation rate normalized by UV irradiance: ln N0/Nuv Z= Dose (μWatt x sec x cm-2) [Kethley 1973] where N0 is the number of surviving microorganisms with no UVGI exposure, NUV is the number of surviving microorganisms following UV exposure, and D is the UVGI dose in μW·s/cm2. Z is the slope of the plot of the natural logarithm of colony count against UV dose: Theoretically, the higher the Z-value for a target microorganism, the greater the A review of airborne susceptibility tb at 50% humidity = quickly(23-42) Erdman strain be. M. to UVGI and the more 33 the microorganism will 48 (44-55) 1 99RB

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref Determination of UV effectiveness Effectiveness: A measure of the ability of an upper-room UVGI system to kill or inactivate microorganisms. This may be expressed as either eACH in decay experiments or the percentage of microorganisms killed or inactivated by UVGI in constant generation experiments. This latter measure of effectiveness may be expressed by the following equation: EUV = 100 × (1 − CUV / C0), where EUV represents the effectiveness of UVGI as a percentage, CUV is the concentration of culturable micro organisms with UVGI exposure, and C0 is the concentration of culturable micro organisms without UVGI exposure. A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref According to First et al [1999]: • When a volume equivalent to the volume of the room enters and is exhausted • 1 ACH well-mixed air removes 63% of air contaminants • 2 ACH well-mixed air removes 84% of air contaminants • Any air disinfection method that is 63% effective produces 1 Equivalent ACH This equivalence is not uncontested A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref In 1997, the Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH) awarded a contract to the University of Colorado to evaluate UVGI to kill or inactivate airborne mycobacteria. • These included: – the irradiance level in the upper room that provides a UVGI dose over time that kills or inactivates an airborne surrogate of M.tb – how to best measure UVGI fluence levels – the effect of air mixing on UVGI performance – the relationship between mechanical ventilation and UVGI systems, – the effects of humidity and photoreactivation, and – the optimum placement of UVGI fixtures. A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES: comparative UVGI efficacy Riley (1976) Miller (1999) Ko (2000) Source Nardell 2010 Micro-organism BCG Mycobacterium BCG parafortuitum Particle size (μ m) 0.5 - 3 0.65 - 2.1 1.1 - 4.7 Suspending 0.2% BSA DW 10% FCS medium Temperature (°C) n/a n/a 15 - 35 4 - 26 RH (%) 25 20, 40 50 - 90 41- 69 Room size (m3) 61 90 46 Mechanical No Yes Yes ventilation ACH 2 2-4 0 6 6-8 6 Mixing fan Yes Yes No during aerosolisation UV output (W) 17 46 99 (28) 99 (28) 36 (10) 59 (15) UV output/ room 0.28 0.75 1.1 1.1 0.78 1.3 size (W/m3) UV fixture type C1 C1&W CN&C2 CN&C2 C2 C2&W UV effectiveness 83 88, 89 98 95 52 ±19 64 ±10 (%) UV effect (ACH) A review of airborne 10 18-19, 33 6-16, 19 9.8 ± 6.4 11.7 ± 7.1

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Xu, et al 2002 – Boulder, Colorado Source Department of Health and Human Services, et al 2009 A review of airborne Source Xu, et al 2003

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Xu, Et al 2002 – UVGI full-scale efficacy studies 5 fixtures, totalling 216 W producing: - avg. 42 μW/cm2 in the irradiated upper zone, - 0.08 μW/cm2 at eye level 250 C 50% RH Spatial distribution of UV measured using actinometry in the upper-room zone with 100% UVGI A review of airborne Source Xu, et al 2003

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Xu, Et al 2002 – Boulder, Colarado • Full scale room studies – 87 m2 test chamber • B. subtilis, M. parafortuitum, and M. bovis. • Two experiments: At 50% RH with all lamps: – constant generation – effectiveness culturable airborne bacteria reduced: – inactivation rate – equivalent ACH • B. subtilis spores - 46% - 80% • M. parafortuitum - 83% - 98% • M. bovis BCG - 96% - 97% Increasing the ventilation rate from 0 to 6 ACH decreased microbial inactivation for M. parafortuitum and B. sublilis spores Reducing lamp numbers decreased A review of airborne effectiveness

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Escombe et al 2009 – Hospital Nacional Dos de Mayo, Lima Airborne transmission study facility with three parallel ward air exposure chambers TB/HIV ward Air injection vent Upward-facing UVGI fixture Simple mixing fan A review of airborne Air extraction Source Escombe, et al 2009

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Escombe et al 2009 – UVGI and Ionisation • 535 days, 150 guinea pigs per enclosure, using a 2-d cycle. • UV-off days: Control and negative ioniser chambers (chamber 1 &2) • UV-on days: UV lights and mixing fans were turned on in the ward (chamber 3) • TB infection in guinea pigs was defined by monthly tuberculin skin tests • control group 35% • ionizers 14 % • UVGI 9.5 % Guinea pigs underwent autopsy to test for TB disease • • control group 8.5% Ground plane Power supply • ionizers 4.3 % • UVGI 3.6 % Insulating spacers Needle tips discharge 25 000 V A review of airborne Source Escombe, et al 2009

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Escombe et al 2009 – UVGI and Ionisation Control UV Lights Ionisers Dust-related outbreak TB Infected animals (% of exposed) Source Escombe, et al 2009 A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref UPPER AIR UVGI Summary Guidance DHHS Temperature 20 - 24 °C Ceiling supply air room t °C - 3 °C ACH <6 RH 30 - 60% min. ave. fluence 12 μW/cm2 ave. UV fluence rate 30 - 50 μW/cm2 Lamps Low-pressure mercury arc or Medium-pressure (low ozone) Irradiance 1.87 W/m2 Power 6 W/m3 Mercury < 5mg Max lower room irradiance 0.2 μW/cm2 (conservative?) CDC/NIOSH REL 6 mJ/cm2 per 8 hours ACGIH TLV 6 mJ/cm2 per 8 hours A review of airborne Ballast harmonic distortion < 10% Ceiling > 2.7m unsheilded Ceiling 2.4 - 2.7m sheilded

STUDIESEscombe et al 2007 – Natural ventilation in LimaOBJECTIVE : to investigate the rates, determinants, and effects of natural ventilationin health care settings.• 5 ‘‘old-fashioned’’ design (built pre-1950) and 3 ‘‘modern’’ design (1970–1990) were studied = 70 naturally ventilated clinical rooms with infectious patients• Compared to 12 post-2000 mechanically ventilated negative-pressure respiratory isolation rooms – CO2 tracer gas technique – 368 experiments – Architectural and environmental variables were measured – Infection risk was estimated for TB exposure (Wells- Riley model) A review of airborne Source: Google 2011 Malta

STUDIESEscombe et al 2007 Source Google 2011Opening windows and doors provided median ventilation of 28 ACH: – >2 x mechanically ventilated negative-pressure rooms ventilated at 12 ACH – 18 times that with windows and doors closed• Facilities built more than 50 years ago, characterised by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms (40 versus 17 ACH)• Even within the lowest quartile of wind speeds, natural ventilation exceeded mechanical• Model predicted that following 24 h exposure to untreated TB patients: – 39% of susceptible individuals in mechanically ventilated rooms – 33% in modern – 11% in pre-1950 naturally ventilated facilities with windows and doors open would become infectiousCONCLUSION: “Opening windows and doors maximises natural ventilation so thatthe risk of airborne contagion is much lower than with … mechanical ventilationsystems.” A review of airborne

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref STUDIES Zhao et al 2009 – Silver-doped Titanium Dioxide nano-Ag/TiO2 and UVA light irradiation can improve the efficiency of bacterial restraining in medical nursing institutions [Zhao et al] A review of airborne Source: Google 2011 Ellis Island

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref References Bolashikov, Z.D. , Melikov, A.K., 2009. Methods for air cleaning and protection of building occupants from airborne pathogens. Building and Environment 44, 1378–1385. doi:10.1016/j.buildenv.2008.09.001. Digel, I., Temiz, Artmann, A., Nishikawa, K., Cook, M., Kurulgan, E.I. Artmann, G.M., 2005. Bactericidal effects of plasma-generated cluster ions. Medical Biological Engineering and Computing 43, 800-807. Department of Health and Human Services., Centers for Disease Control and Prevention., National Institute for Occupational Safety and Health., 2009. Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Healthcare Settings. Escombe, R.A., Moore, D.J.A., Gilman, R.H., Navincopa, M., Ticona, E., Mitchell, B., Noakes, C,. Martı´nez, C., Sheen,P., Ramirez, R., Quino, W., Gonzalez, A., Friedland, J.S., Evans, C.A., 2009. Natural Ventilation for the Prevention of Airborne Contagion. PLoS Medicine 6:3, 0-11. www.plosmedicine.org . Escombe, R.A., Oese, C.C., Gilman, R.H., Navincopa, M., Pan, W., Martı´nez, C., Chacaltana, J., Rodrı´guez, R., Moore, D.J.A., Friedland, J.S., Evans, C.A., 2007. Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission PLoS Medicine 4:2, 309-317. www.plosmedicine.org . Kato, S., Sung,M., 2011. Using UVGI to counter contaminant dispersion. IFHE Digest 2011.

intro I transmission I considerations I techniques I dilution I filtration I UV 123 I PCO I ionisation I advanced distribution I ref References (continued) Kearns, A.M., Barrett, A., Marshall, C., Freeman, R., Magee, J.G., Bourke, S.J., Steward, M., 2000. Epidemiology and molecular typing of an outbreak of tuberculosis in a hostel for homeless men. Journal of Clinical Pathology 53, 122–124. Kowalski, W. 2010. Ultraviolet Germicidal Irradiation Handbook. Springer, New York. ISBN 978-3-642-01998-2. Nardell, E.A., 2010. Progress in the Application of Ultraviolet Germicidal Irradiation. American Society for Photobiology. Powerpoint accessed www.ghdonline . Riley, R.L., Knight, M., Middlebrook, G., 1976. Ultraviolet susceptibility of BCG and virulent tubercle bacilli. American Review of Respiratory Disease 113, 413–418. Xu, P., Peccia, J., Fabian, P., Martyny, J.W., Fennelly, K.P., Hernandez, M., Miller S.L., 2003. Efficacy of ultraviolet germicidal irradiation of upper-room air in inactivating airborne bacterial spores and mycobacteria in full-scale studies. Atmospheric Environment 37, 405–419. Zhao, Y.K., Sung, W.P., Tsai, T.T., Wang, H.J., 2010. Application of Nanoscale Silver-Doped Titanium Dioxide as Photocatalyst for Indoor Airborne Bacteria Control: A Feasibility Study in Medical Nursing Institutions. Journal of Air and Waste Management Association 60:337–345. ISSN:1047-3289.

Architectural Engineering Research Group Dirk Conradie Faatiema Salie Geoff Abbott Jeremy Gibberd Lorato Motsatsi Nkhensani Baloyi Peta de Jager Sheldon Bole Thabang Molefi Tichoana Kumurai Sidney ParsonsSlide 31

Architectural Engineering research group Dirk Conradie Faatiema Salie Geoff Abbott Jeremy Gibberd Lorato Motsatsi Nkhensani Baloyi Peta de Jager Sheldon Bole Thabang Molefi In memory of Dr Sidney ParsonsSlide 32

SAFHE/CEASA 2011 - Airborne disinfection methods

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SAFHE/CEASA 2011 - Airborne disinfection methods — Presentation Transcript

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