Wei-Chung Su This email address is being protected from spambots. You need JavaScript enabled to view it.1, Jinho Lee1, Jinxiang Xi2, Kai Zhang3

1 Department of Epidemiology, Human Genetics and Environmental Sciences, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, USA
2 Department of Biomedical Engineering, Francis College of Engineering, University of Massachusetts, Lowell, Massachusetts, USA
3 Department of Environmental Health Sciences, University at Albany, State University of New York, Albany, New York, USA

Received: September 1, 2021
Revised: October 24, 2021
Accepted: November 29, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.210228  

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Cite this article:

Su, W.C., Lee, J., Xi, J., Zhang, K. (2022). Investigation of Mask Efficiency for Loose-fitting Masks against Ultrafine Particles and Effect on Airway Deposition Efficiency. Aerosol Air Qual. Res. 22, 210228. https://doi.org/10.4209/aaqr.210228


  • Loose-fitting masks were evaluated for mask efficiencies against ultrafine particles.
  • KN95 mask showed a relatively better mask efficiency among all loose-fitting masks tested.
  • The cloth mask showed a generally low mask efficiency compared to other masks tested.
  • Airway deposition efficiencies were decreased due to mask-wearing.


Ultrafine particle (i.e., smaller than 100 nm) in the ambient air is a significant public health issue. The inhalation and deposition of ultrafine particles in the human airways can lead to various adverse health effects. Loose-fitting types of masks are commonly used by the general public in some developing countries for protecting against ultrafine particles in the ambient environment. This research conducted a series of laboratory chamber experiments using two sets of particle sizers and two mannequin heads to study the mask efficiency of selected loose-fitting masks. Results acquired demonstrated that the cloth mask showed a low mask efficiency against ultrafine particles with the mask efficiency generally less than 0.4. The KN95 presented a better mask efficiency among all tested masks with the mask efficiency overall larger than 0.5. In addition, the effect of mask-wearing on the change of ultrafine particle airway deposition efficiency was also investigated in this study. The ultrafine particle deposition efficiency in the airway section studied was found to decrease due to mask-wearing, and the decreases of the deposition efficiencies were similar among all loose-fitting masks tested.

Keywords: Mask efficiency, Loose-fitting mask, Ultrafine particle, Airway deposition efficiency

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