Effect of ventilation improvement during a tuberculosis outbreak in underventilated university buildings

Du, Chun Ru; Wang, Shun Chih; Yu, Ming Chih; Chiu, Ting Fang; Wang, Jann‐Yuan; Chuang, Pei Chun; Jou, Ruwen; Chan, Pei-Ying S.; Fang, Cheng-Chung

doi:10.1111/ina.12639

Cited by 55 publications

(53 citation statements)

References 25 publications

(47 reference statements)

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“…Greater airflow outdoors contributes to greater dispersion, whereas indoors the airflow is restricted by the surrounding walls and ceiling. Ventilation rate and airflow patterns play an important role in airborne transmission of viruses in indoor environments (144)(145)(146). A study of rhinovirus transmission showed that a low ventilation rate increases the risk of exposure to virus-laden aerosols indoors (27,28).…”

Section: Airflow Ventilation and Filtrationmentioning

confidence: 99%

Airborne transmission of respiratory viruses

Wang

Prather

Sznitman

et al. 2021

Science

910

745

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The COVID-19 pandemic has revealed critical knowledge gaps in our understanding of and a need to update the traditional view of transmission pathways for respiratory viruses. The long-standing definitions of droplet and airborne transmission do not account for the mechanisms by which virus-laden respiratory droplets and aerosols travel through the air and lead to infection. In this Review, we discuss current evidence regarding the transmission of respiratory viruses by aerosols—how they are generated, transported, and deposited, as well as the factors affecting the relative contributions of droplet-spray deposition versus aerosol inhalation as modes of transmission. Improved understanding of aerosol transmission brought about by studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requires a reevaluation of the major transmission pathways for other respiratory viruses, which will allow better-informed controls to reduce airborne transmission.

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Section: Airflow Ventilation and Filtrationmentioning

confidence: 99%

Airborne transmission of respiratory viruses

Wang

Prather

Sznitman

et al. 2021

Science

910

745

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“…Therefore, the rate of COVID-19 transmission in schools was higher than the community transmission, and mitigation measures must be implemented in classrooms to reduce the infection risk. Several studies revealed the significant impact of ventilation rate in reducing or preventing the airborne transmission of diseases in indoor environments 6 . There are different recommendations for the minimum required ventilation rate in indoor spaces to achieve an acceptable indoor air quality or preventing indoor airborne transmission.…”

Section: Introductionmentioning

confidence: 99%

Bayesian Calibration of Using CO₂Sensors to Assess Ventilation Conditions and Associated COVID-19 Airborne Aerosol Transmission Risk in Schools

Hou

Katal

Wang

2021

Preprint

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Ventilation rate plays a significant role in preventing the airborne transmission of diseases in indoor spaces. Classrooms are a considerable challenge during the COVID-19 pandemic because of large occupancy density and mainly poor ventilation conditions. The indoor CO2 level may be used as an index for estimating the ventilation rate and airborne infection risk. In this work, we analyzed a one-day measurement of CO2 levels in three schools to estimate the ventilation rate and airborne infection risk. Sensitivity analysis and Bayesian calibration methods were applied to identify uncertainties and calibrate key parameters. The outdoor ventilation rate with a 95% confidence was 1.96±0.31ACH for Room 1 with mechanical ventilation and fully open window, 0.40±0.08 ACH for Rooms 2, and 0.79±0.06 ACH for Room 3 with only windows open. A time-averaged CO2 level < 450 ppm is equivalent to a ventilation rate > 10 ACH in all three rooms. We also defined the probability of the COVID-19 airborne infection risk associated with ventilation uncertainties. The outdoor ventilation threshold to prevent classroom COVID-19 aerosol spreading is between 3-8 ACH, and the CO2 threshold is around 500 ppm of a school day (< 8 hr) for the three schools.

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“…Because CO 2 concentrations increase with the number of occupants in a space, and one or more of the occupants could potentially be infected, it is logical that respiratory disease risk scales upwards with indoor CO 2 levels. Du et al 13 , for example, demonstrated that when CO 2 was reduced to less than 1000 ppm, it was independently associated with a 97 % decrease in tuberculosis incidence among contacts. In 2003, Rudnick and Milton 14 introduced a model that uses CO 2 levels to estimate the risk of airborne transmission of influenza and other respiratory diseases.…”

Section: Introductionmentioning

confidence: 99%

Correlation of Respiratory Aerosols with Metabolic Carbon Dioxide

Kappelt

Russell

Kwiatkowski³

et al. 2021

Preprint

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Respiratory Aerosols from breathing and talking have found wide acceptance as a transmission route for viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies have found particles with diameters ranging from 10 nm to 145 µm, exhibited from different regions in the respiratory system. We present the first chamber study, in which respiratory aerosols have been simultaneously measured with carbon dioxide (CO2) to establish the correlation between the two concentrations. CO2 concentrations are easily available through low-cost sensors and could be used to estimate viral exposure through this correlation, whereas source-specific aerosol measurements are complicated and not possible with low cost sensors. The increase in both PM10 and CO2 was linear over ten minutes in a 2 m3 chamber for all participants, suggesting a strong correlation. On average, talking released more particles than breathing, with 14,600 ± 16,800 min-1 (one-σ standard deviation) and 6,210 ± 5,630 min-1 on average, respectively, while CO2 increased with 139 ± 33 ppm min-1 during talking and 143 ± 29 ppm min-1 during breathing. Assuming a typical viral load of 7 × 106 RNA copies per ml of oral fluid, ten minutes of talking and breathing are estimated to produce 7 and 16 suspended RNA copies, respectively, correlating to a CO2 concentration of around 1.800 ppm in a 2 m3 chamber. This provides a strong argument for keeping indoor spaces well ventilated and shows how CO2 concentrations, measured with low-cost sensors, could be used as a proxy for viral exposure.

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Effect of ventilation improvement during a tuberculosis outbreak in underventilated university buildings

Abstract: This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Cited by 55 publications

References 25 publications

Airborne transmission of respiratory viruses

Airborne transmission of respiratory viruses

Bayesian Calibration of Using CO₂Sensors to Assess Ventilation Conditions and Associated COVID-19 Airborne Aerosol Transmission Risk in Schools

Correlation of Respiratory Aerosols with Metabolic Carbon Dioxide

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Effect of ventilation improvement during a tuberculosis outbreak in underventilated university buildings

Abstract: This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Cited by 55 publications

References 25 publications

Airborne transmission of respiratory viruses

Airborne transmission of respiratory viruses

Bayesian Calibration of Using CO2Sensors to Assess Ventilation Conditions and Associated COVID-19 Airborne Aerosol Transmission Risk in Schools

Correlation of Respiratory Aerosols with Metabolic Carbon Dioxide

Contact Info

Product

Resources

About

Bayesian Calibration of Using CO₂Sensors to Assess Ventilation Conditions and Associated COVID-19 Airborne Aerosol Transmission Risk in Schools