News Central Site

Study evaluates the filtration efficacy of 227 commercially available face masks in Brazil

Publicado em 02 junho 2021

Por Karina Toledo, da Agência FAPESP

The novel coronavirus is transmitted primarily by way of inhalation of saliva droplets or respiratory secretions suspended in air, in order that face overlaying and social distancing are the handiest methods to forestall COVID-19 till sufficient vaccines are available for all. In Brazil, material masks are amongst the most generally used as a result of they’re low cost, reusable and available in a number of colours or designs. However, this sort of face overlaying’s capability to filter aerosol particles of a measurement equal to the novel coronavirus can differ between 15% and 70%, in keeping with a research performed in Brazil by the University of São Paulo (USP).

The research was supported by FAPESP, and the principal investigator was Paulo Artaxo, a professor in the college’s Physics Institute (IF-USP). It was half of an initiative known as (respire! to guarantee entry to secure masks for the college neighborhood. The outcomes are reported in an article in the journal Aerosol Science and Technology.

“We appraised the filtration efficacy of 227 models sold by drugstores and other common types of store in Brazil to see how much genuine protection they afford the general public,” Artaxo advised Agência FAPESP.

The scientists performed a take a look at utilizing a tool that contained a sodium chloride answer and emitted aerosol particles of 100 nanometers. SARS-CoV-2 is about 120 nanometers in diameter. A burst of aerosols was triggered, and particle focus was measured earlier than and after the masks.

As anticipated, surgical masks had been handiest in the take a look at, as had been the FFP2 or N95 fashions licensed for skilled use, filtering 90%-98% of the particles. Next got here masks made of non-woven material (TNT) or polypropylene and offered in many varieties of retailer, with an effectivity of 80%-90%, adopted by these made of peculiar cotton, spandex or microfiber, which filtered 40% on common (15%-70%).

Several components had been crucial in enhancing or lowering the diploma of safety. “Generally speaking, masks with a central seam protect less because the sewing machine makes holes that increase the passage of air. A tightly fitting top edge improves filtration significantly. Some masks made of fabric include fibers of nickel, copper or other metals that inactivate the virus and hence protect the wearer more effectively. There are even electrically charged models that retain more particles. In all cases, however, efficacy drops when the mask is washed because of wear and tear,” mentioned Fernando Morais, first writer of the article. Morais is a PhD candidate at IF-USP and a researcher at the Nuclear and Energy Research Institute (IPEN), an company of the São Paulo State Government.


According to Artaxo, dual-layer cotton masks filtered significantly higher than single-layer fashions, however efficacy was hardly altered by a 3rd layer, which decreased breathability.

“The study innovated in several ways. One was its evaluation of breathability or resistance to air passage,” Artaxo mentioned. “TNT and cotton masks were best in this regard. The FFP2 and N95 models were not as comfortable, but paper masks were the worst. This is important because if a person can’t bear wearing a mask even for five minutes, it’s useless.”

The authors of the article notice that though masks efficacy varies, all sorts assist cut back transmission of the virus, and mask-wearing in conjunction with social distancing is prime to regulate the pandemic. They advocate mass manufacturing of FFP2/N95 masks for distribution free of cost to the common public. This “should be considered in future pandemics”, in keeping with Vanderley John, penultimate writer and coordinator of (respire!, which is organized by USP’s Innovation Agency.

“Transmission of the virus is demonstrably airborne and wearing a mask all the time is one of the best prevention strategies, as well as leaving doors and windows open to ventilate rooms as much as possible,” Artaxo mentioned.


About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public establishment with the mission of supporting scientific analysis in all fields of data by awarding scholarships, fellowships and grants to investigators linked with increased schooling and analysis establishments in the State of São Paulo, Brazil. FAPESP is conscious that the absolute best analysis can solely be executed by working with the greatest researchers internationally. Therefore, it has established partnerships with funding businesses, increased schooling, non-public firms, and analysis organizations in different international locations identified for the high quality of their analysis and has been encouraging scientists funded by its grants to additional develop their worldwide collaboration. You can study extra about FAPESP at and go to FAPESP information company at to maintain up to date with the newest scientific breakthroughs FAPESP helps obtain by way of its many packages, awards and analysis facilities. You might also subscribe to FAPESP information company at

Disclaimer: AAAS and EurekAlert! are usually not liable for the accuracy of information releases posted to EurekAlert! by contributing establishments or for the use of any info by way of the EurekAlert system.