Reduction of exposure to simulated respiratory aerosols using ventilation, physical distancing, and universal masking

Abstract

To limit community spread of SARS‐CoV‐2, CDC recommends universal masking indoors, maintaining 1.8 m of physical distancing, adequate ventilation, and avoiding crowded indoor spaces. Several studies have examined the independent influence of each control strategy in mitigating transmission in isolation, yet controls are often implemented concomitantly within an indoor environment. To address the influence of physical distancing, universal masking, and ventilation on very fine respiratory droplets and aerosol particle exposure, a simulator that coughed and exhaled aerosols (the source) and a second breathing simulator (the recipient) were placed in an exposure chamber. When controlling for the other two mitigation strategies, universal masking with 3‐ply cotton masks reduced exposure to 0.3–3 µm coughed and exhaled aerosol particles by >77% compared to unmasked tests, whereas physical distancing (0.9 or 1.8 m) significantly changed exposure to cough but not exhaled aerosols. The effectiveness of ventilation depended upon the respiratory activity, that is, coughing or breathing, as well as the duration of exposure time. Our results demonstrate that a layered mitigation strategy approach of administrative and engineering controls can reduce personal inhalation exposure to potentially infectious very fine respiratory droplets and aerosol particles within an indoor environment.

Size dependent effectiveness of engineering and administrative control strategies for both short- and long-range airborne transmission control

“…However, the efficiency of masks is highly dependent on the material ltration efficiency and the t to users' face. 7,17,59 If poorly tted, the leakage of a mask can even reach 70-85%. 60 Therefore, even though a high-efficiency mask can achieve a signicant reduction in virus concentration, the impact of other control strategies cannot be ignored.…”

“…4,5 Great efforts have been made to identify effective strategies for controlling both short-and long-range airborne transmissions, with ventilation, ltration, social distancing, and mask wearing being widely adopted. [6][7][8] Ventilation and ltration are mainly designed to reduce long-range airborne transmission. [8][9][10][11] A study by Shen et al 11 found that doubling the ventilation rate could reduce longrange airborne transmission by approximately 37%.…”

EN PRENSA. Graphical-mathematical model to estimate CO2 concentration level as an indicator of SARS-CoV-2 transmission. EN PRENSA

“…Para confirmar el impacto de la interacción T/V, la Figura 3 muestra un comportamiento similar para V/O, lo que evidencia que el factor dominante es la ventilación; por lo tanto, se consideró como un factor fijo en su nivel máximo, ya que bajo esta condición el modelo matemático puede estimar el mayor tiempo o porcentaje de ocupación. Resultados similares se obtuvieron considerando tres variables de control para limitar la exposición al SARS-CoV-2 en ambientes interiores: ventilación, distanciamiento físico y uso de cubrebocas (mascarillas de algodón de 3 capas) que contribuyeron a reducir la exposición a los aerosoles (Coyle et al, 2021).…”

“…Así, la transmisión viral es más probable en ambientes interiores y poco ventilados en comparación con ambientes exteriores o con abundante flujo de aire (Li et al, 2021;Coyle et al, 2021). Por lo tanto, el riesgo de transmisión del SARS-CoV-2 puede aumentar en entornos saturados de exhalaciones humanas, como ocurre en los espacios interiores.…”

Prophylaxis and Remediation for Future Pandemic Pathogens—(Lessons from a Post-COVID World)

“…If dust floats near an object at high voltage, or becomes highly charged, the dust will usually be attracted and then will often stick to the object. The behavior may seem counterintuitive as opposite charges attract, same charges repel, an uncharged dust particle should be unaffected by a charged object [51]. However, viruses have charged patches and can accompany dust and change the charge distribution.…”