Can you use N95 respirators after disinfection? Experts list ways to do so

Can N95 respirators be reused after disinfection? This is a question that scientists seek to answer and they list a few points that can help you do so.

The COVID-19 pandemic shows no signs of abating despite the best efforts of governments and organisations across the world. The current pandemic caused by a new and virulent strain of coronavirus is highly contagious and there is as yet no cure or vaccine for it yet. To deal with the pandemic and contain the alarming spread of the deadly contagion, countries have imposed strict lockdown. But now, it looks like we may be in this situation for a long time to come. So preventive measures must be followed diligently. Other that the usual washing of hands and adhering to social distancing norms, you also have to cover your face with a mask to avoid inhaling any airborne droplets that may contain the virus.

Since the beginning, experts have been telling us about the importance of protective masks. This has led to panic buying by people and also hoarding of masks by some unscrupulous traders. So now most people are making their own masks. The coveted N95 masks are said to be every effective against the COVID-19 virus. But because of scarcity, these are now reserved for healthcare professionals and those who are working actively with infected people. Even for them, sometimes, it may be necessary to reuse the masks because of the shortage. To solve this problem, Stanford University, Stanford Institute for Materials and Energy Sciences and SLAC National Accelerator Laboratory, California, conducted a study to see if N95 respirators can be reused after disinfection.


Researchers sought to determine how we can reuse respirators and other personal protective equipment in these urgent times. According to them, N95 masks contain a fiber layer called ‘melt-blown polypropylene fibers’. This fibre forms a breathable fabric through which you can breathe. These fibers are electrostatically charged so that it can filter out and protect you from smaller particles such as viruses. However, they do admit that this study did not test the ability of the disinfected masks to filter out the coronavirus.


Due to the acute shortage of N95 masks, healthcare personnel are now reusing these to keep themselves safe. Let us see how you can disinfect your mask.


Results of the study reveal that if you heat your N95 mask at 70 °C for up to 5 minutes, it can effectively kill all viruses. This is the most effective and easy way by which you can keep reusing your mask. According to the researchers, if the melt-blown fabrics and the N95 masks were heated for less than or equal to 85 °C at less than 100 per cent relative humidity, it was very effective. They say that this method was ‘the most promising, non-destructive method for the preservation of filtration properties’. You can repeat this process for up to 50 times. Even if you lower the bar to 30 per cent relative humidity, at 100 °C the filtration ability remained unchanged even after 20 cycles.

Ultraviolet (UV) Irradiation

Another way of disinfecting, according to researchers is Ultraviolet (UV) irradiation. The team saw that the masks and fabrics were able to withstand up to 10 cycles of irradiation. But after about 20 such cycles, they noticed a ‘small degradation’ of the fabric. There may be some effect on the sealing and the material strength too. Moreover, they were also not very clear about the exact dose of UV radiation that may be able to effectively disinfect the masks.


Researchers say that if you use steam, household bleach, soap and aerosols, it may cause degradation of the filtration capacity of the masks. This will leave the wearer exposed and vulnerable.  Alcohol or chlorine bleach solution can also bring down the filtration capacity from 96 per cent to 56 per cent. This is because these methods will alter the electrostatic charge within the fabric, say researchers.


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