Improving the Environmental Controls at a Homeless Shelter to Assist in Reducing the Probability of Airborne Transmission of <i>Mycobacterium tuberculosis</i>: A Case Study

Coffey, Christopher C.; Hudnall, Judith B.; Martin, Stephen B.

doi:10.1177/1420326x09103008

Cited by 9 publications

(6 citation statements)

References 8 publications

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“…Specifically, for example, homeless shelters commonly use a central HVAC system equipped with low-efficiency filters (i.e., MERV 8 or below) 47 at the ceiling and have an outside air supply that is below ASHRAE’s standard (i.e., 15 cfm per person). 48 To mitigate airborne transmission risks in these places, we can place our air cleaner below the air return location in the room to serve as a low-cost booster of their central HVAC system with improved flow rate and filtration efficiency. For large size shelters, we propose to use multiple air cleaners (owing to their low cost) distributed in the space and placed near the potential sources of emission for optimal risk mitigation.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Airborne transmission of COVID-19 and mitigation using box fan air cleaners in a poorly ventilated classroom

Liu

Elson

et al. 2021

Physics of Fluids

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Many indoor places, including aged classrooms and offices, prisons, homeless shelters, etc., are poorly ventilated but resource-limited to afford expensive ventilation upgrades or commercial air purification systems, raising concerns on the safety of opening activities in these places in the era of the COVID-19 pandemic. To address this challenge, using computational fluid dynamics, we conducted a systematic investigation of airborne transmission in a classroom equipped with a single horizontal unit ventilator (HUV) and evaluate the performance of a low-cost box fan air cleaner for risk mitigation. Our study shows that placing box fan air cleaners in the classroom results in a substantial reduction of airborne transmission risk across the entire space. The air cleaner can achieve optimal performance when placed near the asymptomatic patient. However, without knowing the location of the patient, the performance of the cleaner is optimal near the HUV with the air flowing downwards. In addition, we find that it is more efficient in reducing aerosol concentration and spread in the classroom by adding air cleaners in comparison with raising the flow rate of HUV alone. The number and placement of air cleaners need to be adjusted to maintain their efficacy for larger classrooms and to account for the thermal gradient associated with a human thermal plume and hot ventilation air during cold seasons. Overall, our study shows that box fan air cleaners can serve as an effective low-cost alternative for mitigating airborne transmission risks in poorly ventilated spaces.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Airborne transmission of COVID-19 and mitigation using box fan air cleaners in a poorly ventilated classroom

Liu

Elson

et al. 2021

Physics of Fluids

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“…The key question is how to respond effectively. Reported interventions have included a mobile radiographic screening program in Rotterdam[ 29 ], and improved ventilation plus ultraviolet light fixtures in a shelter in St. Louis[ 30 ]. Improvements to the management of latent TB infection would likewise be important in this context.…”

Section: Discussionmentioning

confidence: 99%

Tuberculosis and homelessness in Montreal: a retrospective cohort study

et al. 2011

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BackgroundMontreal is Canada's second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000. The objectives of this study were to describe the epidemiology of TB among homeless persons in Montreal and assess patterns of transmission and sharing of key locations.MethodsWe reviewed demographic, clinical, and microbiologic data for all active TB cases reported in Montreal from 1996 to 2007 and identified persons who were homeless in the year prior to TB diagnosis. We genotyped all available Mycobacterium tuberculosis isolates by IS6110 restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping, and used a geographic information system to identify potential locations for transmission between persons with matching isolates.ResultsThere were 20 cases of TB in homeless persons, out of 1823 total reported from 1996-2007. 17/20 were Canadian-born, including 5 Aboriginals. Homeless persons were more likely than non-homeless persons to have pulmonary TB (20/20), smear-positive disease (17/20, odds ratio (OR) = 5.7, 95% confidence interval (CI): 1.7-20), HIV co-infection (12/20, OR = 14, 95%CI: 4.8-40), and a history of substance use. The median duration from symptom onset to diagnosis was 61 days for homeless persons vs. 28 days for non-homeless persons (P = 0.022). Eleven homeless persons with TB belonged to genotype-defined clusters (OR = 5.4, 95%CI: 2.2-13), and ten potential locations for transmission were identified, including health care facilities, homeless shelters/drop-in centres, and an Aboriginal community centre.ConclusionsTB cases among homeless persons in Montreal raise concerns about delayed diagnosis and ongoing local transmission.

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“…There is now an increasing requirement and focus for research into the dispersion and transmission of pathogens and pollutants within and around a building environment (e.g. residential building, hospital and hotel) [15][16][17][18], particularly in high-rise residential (HRR) buildings and public places [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Pollutant Dispersion in the Re-entrance Space of a High-rise Residential Building, Using Wind Tunnel Simulations

Wang

Niu

Liu

et al. 2010

Indoor and Built Environment

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This paper investigates the likely route of dispersion of airborne pollutants and pathogenic agents in the re-entrance space of a high-rise residential (HRR) building in Hong Kong. A 1 : 150 scaled HRR building, a 30 storeys tall model was tested in a wind tunnel with simulated atmospheric boundary layer flow. Tracer gas, propane released from the lower, middle and upper parts of the building, was measured by flame ionisation detection and this was used to simulate the air pollutant dispersion within the re-entrance space. There were a total of 495 measurements, tested under five different wind directions at 99 measurement points on windows locations of every floor of the modelled building. The tracer gas concentration profiles obtained would illustrate the pollutant dispersion and transmission routes under the different wind effect. The results showed that the airborne pollutants or pathogenic agents could be dispersed mainly along the vertical routes, posing a potential risk to the adjacent neighbours immediately above the source location. Wind direction could also affect the dispersion. The findings of this study should inform the development of ventilation strategies for HRR buildings and would guide building design to minimise transmission of airborne diseases or harmful pollutants within buildings.

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Improving the Environmental Controls at a Homeless Shelter to Assist in Reducing the Probability of Airborne Transmission of Mycobacterium tuberculosis: A Case Study

Cited by 9 publications

References 8 publications

Airborne transmission of COVID-19 and mitigation using box fan air cleaners in a poorly ventilated classroom

Airborne transmission of COVID-19 and mitigation using box fan air cleaners in a poorly ventilated classroom

Tuberculosis and homelessness in Montreal: a retrospective cohort study

Assessment of Pollutant Dispersion in the Re-entrance Space of a High-rise Residential Building, Using Wind Tunnel Simulations

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