Ventilation and air cleaning to limit aerosol particle concentrations in a gym during the COVID-19 pandemic

Blocken, Bert; Druenen, Thijs van; Ricci, Alessio; Kang, Luyang; Hooff, T. van; Qin, Ping; Xia, Liang; Ruiz, Claudio Alanis; Arts, J.H.E.; Diepens, Jan; Maas, Geert-Jan; Gillmeier, Stefanie; Vos, Steven; Brombacher, Aarnout

doi:10.1016/j.buildenv.2021.107659

Cited by 139 publications

(91 citation statements)

References 79 publications

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“…It is also promising to filter the viral aerosols with air cleaners, as suggested in Ref. [ 50 ] for a gym. Meanwhile, the exposure time is an important factor to the infection risk (as in Eq.…”

Section: Discussionmentioning

confidence: 99%

Study on ventilation rates and assessment of infection risks of COVID-19 in an outpatient building

Tang

2021

Journal of Building Engineering

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A modified Wells-Riley model combining the airborne route and close contact route was proposed to predict the infection risks of coronavirus disease 2019 (COVID-19) in main functional spaces of an outpatient building in Shenzhen, China. The personnel densities and ventilation rates in the 20 waiting rooms, outpatient hall and hospital street were on-site measured. The average fresh air volume per person and occupant area per person in the 20 waiting rooms were 77.6 m 3 /h and 6.47 m 2 /per, satisfied with the Chinese standard. The average waiting time of the occupants was 0.69 h. Thus, assuming the proportion of infected people in the outpatient building was 2%, the daily average infection probabilities of COVID-19 in the 20 waiting rooms were 0.19–1.88% with a reasonable setting of the quanta produced by an infector ( q = 45 quanta/h) and the effective exposure dose of pathogen per unit close contact time ( β = 0.05 h −1 ). The design of the semi-closed hospital street with a height of 24 m improved its natural ventilation with a fresh air volume per person of 70–185 m 3 /h and further dilute the viral aerosol and decreased the infection risk to a negligible level (i.e., below 0.04% with an infector proportion of 2%). The assessment method provides real-time prediction of indoor infection risk and good assist in spread control of COVID-19.

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Section: Discussionmentioning

confidence: 99%

Study on ventilation rates and assessment of infection risks of COVID-19 in an outpatient building

Tang

2021

Journal of Building Engineering

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“… 34 Such simplified modeling has also been employed for COVID-19 risk assessment. 36,38 On the other hand, at the expense of notably higher computational costs and model complexity, CFD-based modeling can provide added insight into spatial evolution of aerosols produced by various expiratory events in realistic indoor environments. Along these lines, a number of studies have modeled airborne spread of COVID-19; 17,39 however, all models rely on quantitative results from experimental studies for an array of input parameters, such as the initial number and size distribution of aerosol particles and initial velocities and duration of expiratory events.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of indoor aerosol dispersion and accumulation in the context of COVID-19: Effects of masks and ventilation

et al. 2021

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The ongoing COVID-19 pandemic has highlighted the importance of aerosol dispersion in disease transmission in indoor environments. The present study experimentally investigates the dispersion and build-up of an exhaled aerosol modeled with polydisperse microscopic particles (approximately 1 μ m mean diameter) by a seated manikin in a relatively large indoor environment. The aims are to offer quantitative insight into the effect of common face masks and ventilation/air purification, and to provide relevant experimental metrics for modeling and risk assessment. Measurements demonstrate that all tested masks provide protection in the immediate vicinity of the host primarily through the redirection and reduction of expiratory momentum. However, leakages are observed to result in notable decreases in mask efficiency relative to the ideal filtration efficiency of the mask material, even in the case of high-efficiency masks, such as the R95 or KN95. Tests conducted in the far field ( distance from the subject) capture significant aerosol build-up in the indoor space over a long duration ( ). A quantitative measure of apparent exhalation filtration efficiency is provided based on experimental data assimilation to a simplified model. The results demonstrate that the apparent exhalation filtration efficiency is significantly lower than the ideal filtration efficiency of the mask material. Nevertheless, high-efficiency masks, such as the KN95, still offer substantially higher apparent filtration efficiencies (60% and 46% for R95 and KN95 masks, respectively) than the more commonly used cloth (10%) and surgical masks (12%), and therefore are still the recommended choice in mitigating airborne disease transmission indoors. The results also suggest that, while higher ventilation capacities are required to fully mitigate aerosol build-up, even relatively low air-change rates ( ) lead to lower aerosol build-up compared to the best performing mask in an unventilated space.

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“…Heavier particles are strongly influenced by gravity, and fall down within a few meters, thereby contributing to virus transmission between individuals over relatively short distances. At this point, it needs to be emphasized that physical parameters such as relative humidity, the ambient air temperature, and the intensity of fluid turbulence influence the range and time particles are suspended in air [14][15][16][17][18][19][20][21][22]. Lighter particles (aerosols) in turn can stay in the air for quite a long time and could transfer the virus over larger distances [23,24].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Aerosol and CO2 Dispersion for Evaluation of COVID-19 Infection Risk in a Concert Hall

Schade

Reimer

Seipenbusch³

et al. 2021

IJERPH

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The dispersion of small aerosols in a concert hall is experimentally studied for estimating the risk of infection with SARS-CoV-2 during a concert. A mannequin was modified to emit an air stream containing aerosols and CO2. The aerosols have a size distribution with a peak diameter (δ) close to 0.3 µm and a horizontal initial particle velocity (vp,x ) of 2.4 m/s. The CO2 -concentration (c) emitted simultaneously is 7500 ppm. It is investigated, if the spatial dissipation of aerosols and CO2 can be correlated. This would allow the use of technically easier CO2 measurements to monitor compliance with aerosol concentration limits. Both aerosol and CO2 concentrations are mapped by different sensors placed around the mannequin. As a result, no significant enrichment of aerosols and CO2 was obtained outside a radius of 1.5 m when the fresh air ventilation in the concert hall has a steady vertical flow with a velocity of vg,z= 0.05 m/s and the installed ventilation system was operating at an air change rate per hour (ACH) of 3, corresponding to an air exchange rate of 51,000 m3/h. A Pearson correlation coefficient of 0.77 was obtained for CO2 and aerosol concentrations measured simultaneously at different positions within the concert hall.

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Ventilation and air cleaning to limit aerosol particle concentrations in a gym during the COVID-19 pandemic

Cited by 139 publications

References 79 publications

Study on ventilation rates and assessment of infection risks of COVID-19 in an outpatient building

Study on ventilation rates and assessment of infection risks of COVID-19 in an outpatient building

Experimental investigation of indoor aerosol dispersion and accumulation in the context of COVID-19: Effects of masks and ventilation

Experimental Investigation of Aerosol and CO2 Dispersion for Evaluation of COVID-19 Infection Risk in a Concert Hall

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