Study of ventilation and virus propagation in an urban bus induced by the HVAC and by opening of windows

Corzo, Santiago F.; Ramajo, Damián E.; Idelsohn, Sergio

doi:10.1016/j.cma.2022.115387

Cited by 7 publications

(8 citation statements)

References 21 publications

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“…The COVID-19 pandemic has provoked a renewed interest in methods to predict the risk of infection spread [ 53 , 54 , 55 , 56 , 57 , 58 ], both probabilistic and deterministic, applied to a variety of settings (indoor, outdoor, public transportation [ 59 ], etc. ), as well as tools [ 60 , 61 , 62 ] for direct application.…”

Section: Methodsmentioning

confidence: 99%

Response to the COVID-19 Pandemic in Classrooms at the University of the Basque Country through a User-Informed Natural Ventilation Demonstrator

Rodríguez-Vidal

Martín-Garín

Quintial

et al. 2022

IJERPH

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The COVID-19 pandemic has generated a renewed interest in indoor air quality to limit viral spread. In the case of educational spaces, due to the high concentration of people and the fact that most of the existing buildings do not have any mechanical ventilation system, the different administrations have established natural ventilation protocols to guarantee an air quality that reduces risk of contagion by the SARS-CoV-2 virus after the return to the classrooms. Many of the initial protocols established a ventilation pattern that opted for continuous or intermittent ventilation to varying degrees of intensity. This study, carried out on a university campus in Spain, analyses the performance of natural ventilation activated through the information provided by monitoring and visualisation of real-time data. In order to carry out this analysis, a experiment was set up where a preliminary study of ventilation without providing information to the users was carried out, which was then compared with the result of providing live feedback to the occupants of two classrooms and an administration office in different periods of 2020, 2021 and 2022. In the administration office, a CO2-concentration-based method was applied retrospectively to assess the risk of airborne infection. This experience has served as a basis to establish a route for user-informed improvement of air quality in educational spaces in general through low-cost systems that allow a rational use of natural ventilation while helping maintain an adequate compromise between IAQ, comfort and energy consumption, without having to resort to mechanical ventilation systems.

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Section: Methodsmentioning

confidence: 99%

Response to the COVID-19 Pandemic in Classrooms at the University of the Basque Country through a User-Informed Natural Ventilation Demonstrator

Rodríguez-Vidal

Martín-Garín

Quintial

et al. 2022

IJERPH

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“…It has been shown that in the motionless case, high probabilities of infection occur in the surrounding area of the emitter, and mechanical ventilation can reduce this risk down to only 3%, and down to <1% for an HVAC system supplying 25% of fresh air. [7] There are also simulative studies on the effect of measures for reducing the risk of infection. Chen et al found that covering a cough or turning the head away can prevent the receptor's direct exposure due to significantly reduced horizontal velocity.…”

Section: Doi: 101002/gch2202300008mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fates of Emitted Particles Depending on Mask Wearing Using an Approach Validated Across Spatial Scales

2023

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The spread of emitted potentially virus-laden aerosol particles is known to be highly dependent on whether a mask is worn by an infected person and on the emission scenario, i.e., whether the person is coughing, speaking, or breathing. The aim of this work is to investigate in detail the fates of particles emitted by a person wearing a perfectly fitting, a naturally fitted mask with leakage, and no mask depending on the emission scenario. Therefore, a two-scale numerical workflow is proposed where parameters are carried through from a micro-scale where the fibers of the mask filter medium and the aerosol particles are resolved to a macro-scale and validated by comparison to experimental measurements of fractional filtration efficiency and pressure drop of the filter medium as well as pressure drop of the mask. It turns out that masks reduce the number of both emitted and inhaled particles significantly even with leakage. While without a mask, the person opposite of an infected person is generally at the highest risk of being infected, a mask worn by an infected person speaking or coughing will deflect the flow leading to the fact that the person behind the infected person might inhale the largest number of aerosol particles.

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“…Many studies addressed airborne transmission in airplane cabins 12,13 high-speed trains 6,14 and coach intercity buses. 15 Specific research was done to understand the COVID-19 transmission in coach buses, 16,17 urban buses, [18][19][20] cars, 21 supermarkets, class rooms, 22 and crowded generic public places with walking people. 10 Mathai et al 21 applied the Eulerian method to investigate the effect of the indoor flow on air concentration inside a car cabin under different open/close windows and mechanical ventilation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The open windows model combined with the W-R risk model allowed to conclude that the transmission risk should be reduced to negligible values by traveling with only a few windows opened even for low bus speed conditions. 19 This article investigates the virus transmission through ballistic and aerosol mechanisms inside an urban bus. The effect of the mechanical ventilation is investigated in depth under different heat, ventilation and air conditioning (HVAC) configurations and renewal ratios.…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics simulation of airborne COVID transmission in urban bus with different HVAC configurations

Ramajo

Corzo

2023

SIMULATION

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The HVAC systems in closed buses promote high particle spread. Lagrangian particle tracking simulations were carried out to evaluate airborne COVID transmission through droplets emitted by sneezing while Eulerian simulations were performed to account for the spread of aerosols emitted by breathing. The position of passengers as well as the effect of three HVAC configurations were evaluated. On one hand, it was concluded that large droplets can travel more than 3 m without being significantly affected by the inflow conditions, but small droplets are easily dispersed by the airflow, and many of them are captured by the HVAC systems. On the other hand, the HVAC systems quickly spreads aerosols along the whole of the bus, increasing the average risk for all passengers, but sensibly reducing the high local risks observed under motionless inflow conditions. The transmission risk was calculated by applying the Wells-Riley model, concluding that the transmission risk for a 20-min trip could remain below 0.5% if HVAC configurations with many inlet/outlet vents are implemented, and the passengers remain in silence and wear face masks.

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Study of ventilation and virus propagation in an urban bus induced by the HVAC and by opening of windows

Cited by 7 publications

References 21 publications

Response to the COVID-19 Pandemic in Classrooms at the University of the Basque Country through a User-Informed Natural Ventilation Demonstrator

Response to the COVID-19 Pandemic in Classrooms at the University of the Basque Country through a User-Informed Natural Ventilation Demonstrator

Fates of Emitted Particles Depending on Mask Wearing Using an Approach Validated Across Spatial Scales

Computational fluid dynamics simulation of airborne COVID transmission in urban bus with different HVAC configurations

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