The study also evaluated 75% ethanol effectiveness in cleaning N95 masks and, according to the results, the filtering capacity of these models decreases.
Although they are already part of the daily life of the population, there are still doubts about the correct way to use face masks. And we’re not talking about those people who use them with their noses out. One of the issues that is still being studied is the best way to clean the accessory without losing its ability to stop the new coronavirus.
With that in mind, scientists in South Korea and Japan have conducted a study that compares and analyzes the performance and differences of the filters used in the masks after being cleaned with ethanol. The research took into account filtration efficiency, rate of air flow, and the properties of the masks after cleaning.
To carry out the tests, the scientists used N95 masks, made with a melt-blown filter, and nanofiber models. First, the team sprayed 75% ethanol on the filters and left them to air dry. Then, another test was performed, in which the materials were dipped in a 75% ethanol solution and placed to air dry.
The result showed that spraying the filter three times or leaving it in the ethanol solution for more than 5 minutes are effective cleaning practices, neutralizing the presence of pathogens. However, the effectiveness of the melt-blown filter decreased by up to 64% when the N95 masks were reused. On the other hand, the nanofiber filters, when reused 10 times and cleaned with ethanol spray or by dipping them in ethanol for 24 hours, still maintained a high filtration efficiency.
The research team attributed this difference to the decrease in static electricity in the melt-blown filters after cleaning – they are responsible for filtering the particles in the N95 mask. However, the nanofiber does not depend on static electricity, but filters according to the size of the pores on the surface of the material, which is not deformed by ethanol.
This means that the two mask filters have similar filtering performance in their initial use, but only the nanofiber filters can be reused several times if cleaned with ethanol.