Special Issue on COVID-19 Aerosol Drivers, Impacts and Mitigation (IX)

Amit Kumar This email address is being protected from spambots. You need JavaScript enabled to view it., D.N. Sangeetha, Ramani Yuvaraj, M. Menaka, Venkatesan Subramanian, Balasubramanian Venkatraman

Radiological and Environmental Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India


Received: July 9, 2020
Revised: September 11, 2020
Accepted: September 11, 2020

 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.2020.06.0349  

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Cite this article:

Kumar, A., Sangeetha, D.N., Yuvaraj, R., Menaka, M., Subramanian, V.,  Venkatraman, B. (2021). Quantitative Performance Analysis of Respiratory Facemasks Using Atmospheric and Laboratory Generated Aerosols Following with Gamma Sterilization. Aerosol Air Qual. Res. 21, 200349. https://doi.org/10.4209/aaqr.2020.06.0349


  • Effect of gamma sterilization on FE of N95, surgical and cloth facemask.
  • FE Evaluation of various facemask under different breathing rate and aerosol sizes.
  • No significant difference between surgical and cotton mask for droplet prevention.
  • Cotton mask is reusable could be a potential substitute for surgical mask.
  • Homemade masks have a very low effectiveness compared to certified mask like N95.


The emergence of the recent COVID-19 pandemic has rendered mandatory wearing of respiratory masks by infected persons, frontline workers, security personnel and members of the public. This has caused a sudden shift of focus, and significant demand on availability, effectiveness, reuse after sterilisation and development of facemask. Toward this, three types of masks viz. N95, non-woven fabric and double layer cotton cloth are being used by the majority of the population across the world as an essential inhalation protective measure for suppressing the entry of virus-laden respiratory droplets. The Filtering Efficiency (FE) of these masks are tested for atmospheric and laboratory-generated aerosols of size 1.0 µm and 102.7 nm particles before and after sterilisation and the two flow rate conditions corresponding to normal breath rate and during sneezing/coughing. Sterilisation is carried out using a gamma irradiator containing Co-60 source for the two-dose exposures viz. 15 kGy and 25 kGy. The FE of surgical and cloth masks is found to be in the range of 15.76 ± 0.22 to 22.48 ± 3.92%, 49.20 ± 8.44 to 60 ± 7.59% and 73.15 ± 3.73 to 90.36 ± 4.69% for aerosol sizes 0.3–5.0, 1.0–5.0 and 3.0–5.0 µm atmospheric aerosols respectively. The FE of cloth and surgical masks ranges from 45.07 ± 6.69% to 63.89 ± 4.44% and 56.58 ± 1.69% to 83.95 ± 1.04% for 1.0 µm laboratory-generated aerosol for two flow rate, control and irradiated conditions. The FE of N95 mask is found to be more than 95% for atmospheric aerosol, and 1.0 µm laboratory-generated aerosol. However, FE reduced to about 70% for most penetrating particle size after sterilisation. Further, FE reduced to 84% for the particle > 0.3 µm and to 87% for the particle < 0.3 µm after sterilisation. The reduction in FE for N95 mask after sterilization is associated with the reduction of electrostatic interaction of filter medium with particles laden in the air stream. Instead of disposing of N95 masks after a single use, they can be reused a few times as N70 mask during this pandemic crisis after sterilisation. The use of cotton cloth masks in the general public serves fit for the purpose than surgical masks.

Keywords: COVID-19, N95 facemask, Non-woven fabric mask, Cloth mask, Gamma sterilization

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