And The Spread of Airborne Infectious Disease Indoor

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Motivation of the Work

W Airborne transmission disease

httpo:r/k/wplwacwe.eaantd Ind M. Tuberculosis [International Union Against .l o Tuberculosis and Lung Disease]

Measles [Department of Health, HKSAR Govt,]

th.se/oarerAoesroolsso2l0s122012 Infamous outbreak cases in various environments

A TB outbreak case in an economy cabin on a flight from Chicago to Honolulu in April 1994. (Kenyon et al. 1996)

AMOY garden was the most seriously affected location during the 2003 SARS outbreak, with over 300 infected people. (Li et al. 2004)

GuriedceohlAiWmntStemHposR:reo/kA/nnwpEdlA'awsaticrwiobe.noearannedTIrnansmVEisNsiTWoILnHADTOIiOsNeNAaTGsUeURICADoLEnLItNroEl ? A strategic research agenda has been t d developed to address the role of HVAC systems .l o in the spread of infectious disease; th. or ? The topic is included in ASHRAE's future s A strategic plans; e/ e ? Further research should be conducted to a r understand how reducing the energy footprint e o of buildings will impact infectious disease r s transmission; o o ? Further research should be conducted on so ls engineering controls to reduce infectious

disease transmission. The document

ls 2 summarizes the control strategies available and 2 0 the occupancy categories in which these 01 12 controls can be used. The research priority for

each control is provided. Filtration and UVGI

2 controls research are given top priority because

? For natural ventilation, the following minimum hourly averaged ventilation rates should be provided:

? 160 l/s/patient (hourly average ventilation rate) for airborne precaution rooms (with a minimum of 80 l/s/patient) (note that this only applies to new health-care facilities and major renovations);

? 60 l/s/patient for general wards and outpatient departments; and

? 2.5 l/s/m3 for corridors and other transient spaces without a fixed number of patients; however, when patient care is undertaken in corridors during emergency or other situations, the same ventilation rate requirements for airborne precaution rooms or general wards will apply.

less is known about how these controls can be

applied in buildings and HVAC systems to

decrease disease events.

ASHRAE. 2009. ASHRAE Position Document on Airborne Infectious Diseases. WHO. 2009. Natural Ventilation for Infection Control in Health-Care Settings.

Formulation of the Problem

hWork - Expiratory droplets and droplet ttp pl nuclei can be airborne carriers for

a various pathogens (e.g. M. :// ce Tuberculosis, measles, influenza,

ww a etc).

w.eant.dlthIn.sdoor A [Department of Medical Microbiology, e/ e Edinburgh University]

- Epidemiology studies showed that these infectious diseases can be transmitted indoors following the ventilation air.

aerosroosols Pathogen-laden ls20122012 Aerosols

Inhalation

Infectious Source

Solid Surface (Fomite)

Susceptible

Epidemiologic Approach

Wor The epidemiology profession has developed a number of widely accepted steps ht kp to investigate disease outbreaks.

tp://wlwace an Disease w.e d In outbreak

Verify the diagnosis related to the outbreak

Identify the existence of the

outbreak

at.lth doo Prevent .se/ar Aer Develop and er os implement control o o and prevention

sols2l0s122012 systems

Create a case definition to define who/what is included as a case

Map the spread of the outbreak

Study & refine hypothesis

Develop a hypothesis

? ? ? ? ? ?

SHWAWAinnozhheyywaahcmdttWtthithaiseSspaotrettn:rreuth/ikhdcd/botwpeeryhudolwoeattipnotificwoorlfaeeern.fireetcraaesbo-attnsdioedftou.dursitlnnsst?hchIppeenerD.eeiisdstnenerehkosfxpde/?eeohaoc?freatisrnilrAooietfoumeeedssdcroodtdt?ilhrsiossEoeoe2nxpal0shsrlsu1eiaes22rtukfs0as?1tc2eeds??

Wo Studies on Expiratory Aerosol Size Distribution httprkpla ? Expiratory droplets evaporate to nuclei and the diameter may reduce

:// ce to around half of the initial size. The smaller nuclei can be ww an suspended in air. w. d ? Collecting media and microscopic measurement were applied to eat Ind reveal the size distribution of expiratory aerosols by numerous .lth oo studies, such as Duguid, 1946 and Louden and Roberts, 1967. .s r A ? The geometric mean diameter of particles from coughing were 12 e/a er m from Duguid and 14 m from Loudon and Roberts. (Nicas et al. er os 2005) osolso2l0s12012 Duguid J.P. 1946. The size and duration of air-carriage of respiratory droplets and droplet-nuclei. J. Hyg, 4, 471?480. 2 Loudon R.G, and Roberts R.M. 1967. Droplet expulsion from the respiratory tract. Am. Rev. Resp. Dis., 95, 435?442.

Nicas M, Nazaroff W.W, and Hubbard A. 2005. Toward understanding the risk of secondary airborne infection: emission of respiratory pathogens. Journal of Occupational and Environmental Hygiene, 2:3, 143-154.

beTMCPfaPMrvxrIIhoeaoVVeSeheuxamatraAgmisuartmlhuvhaehmgedWeruntdieeaeirnotmgexsadpoguvoeuspgotf:rvbrfiehoo/lrklee1yu/oefnwcm0lprmwdoSaCo.lEeMwc2neuoavrxnimgPgutoacwrpteyhSglat/eiudoeh.nrsoavemna.gafenfvfaterleldacncooootdoro.wdmvcrpiluueyfaitatgrghdrIr1ryoAhnahit..emftiesw5dvrcdaeroeeloattoefmw0los/odrosa.oca1ico23r0efoms1i85lf.turA.e.f2ySo2tn8r0r7ieooetfm.zsmoe2mretn1o/oor5r/t,.Dsl-17ss20sd,1t..0i9io.i.s2w6dsl76t.lv-t0a0i0rs8aotlil1l.hbn/l.52u2csuln0,e/tts1sieo,2enrs:

Holmgren H, Ljungstrom E, Almstrand A.C, Bake B, and Olin A.C. 2010. Journal of Aerosol Science, 41, 439-446. Gupta J.K, Lin C.H, and Chen Q. 2009. Indoor Air, 19:517-525. VanSciver M, Miller S, and Hertzberg J. 2011. Aerosol Science and Technology, 45:415-422. Zhu S, Kato S, and Yang J.H. 2006. Building and Environment, 41, 1691?1702.

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