As a result of the COVID-19 pandemic, the demand for certain medical supplies increased tremendously, particularly during the peaks of COVID-19 cases in the United States. Items like surgical masks, N95 masks, KN95 masks, and face shields became extremely necessary in hospitals, which would have to buy them in bulk and wholesale to protect their workers.
However, this demand has increased so much that the production of these items, particularly N95 respirators, hasn’t been sufficient, resulting in shortages of these disposable face masks in the USA. Now, it’s very difficult to find them for sale online or in physical stores, which is why decontamination processes have been one of the most important topics for research during the pandemic.
Unlike reusable cloth masks, which can be used by kids, N95 masks can’t be cleaned and reused using conventional cleaning methods. So, in this article, we’ll discuss the use of a conventional oven found in most households to decontaminate these masks.
What is an N95 mask?
You’ve probably heard about some of the most popular N95 masks: the 3M N95 masks. They have multiple models, including the 3M 8210, 3M 8511, and the 3M 1860. Each of them has different uses, since N95 masks can filter out a wide variety of particles, and can be used in different work settings.
The particles N95 respirators can filter out include dust, pollen, metals, smoke, and bioaerosols that include viruses like the flu or the coronavirus. These particles have in common two things: they don’t contain any oil, and are airborne, meaning that their size can be as small as 0.3 microns.
The name N95 means that the respirator is not resistant to oil and it has a filtration efficacy of 95% against airborne particles. This is established by the National Institute for Occupational Safety and Health, or NIOSH for short. This institution regulates respirators in the USA, and their approval legitimizes the mask.
NIOSH-approved respirators, which have also been tested and approved by the Food and Drug Administration (FDA) to be used as a medical device, are the best face masks for virus protection in healthcare settings specifically for their antiviral properties.
Sterilizing N95 masks in an oven
As COVID-19 cases start to rise again, the demand for personal protective equipment in hospitals and other healthcare centers is expected to result in another wave of shortages. These have primarily affected the N95 mask, which is considered the most valuable item healthcare providers can use to protect themselves.
In these situations, decontamination and reuse of respirators has been a common practice in hospitals and other healthcare facilities, since buying these disposable face masks in bulk or wholesale is not possible for many of them. Instead of leaving their workers unprotected, sterilization techniques have been the new normal for these masks, which are intended for single-use only.
The researchers at the Lamont-Doherty Earth Observatory at Columbia University started to investigate some safe ways to decontaminate and reuse all types of disposable face masks.
They published their research in April of last year, which showed that “baking” certain types of medical-grade masks, including N95 respirators and surgical masks, at a temperature of 170 degrees Fahrenheit didn’t interfere with the respirator’s antiviral filtering properties. This was maintained for up to 10 cycles of sterilization using a conventional oven found in most households.
According to the Food and Drug Administration (FDA), however, not every N95 mask model is designed to be disinfected and reused. The decontamination of each model has to be assessed individually, taking into consideration the specific instructions provided by the manufacturer or a third-party organization. The Centers for Disease Control and Prevention (CDC) clearly state that these instructions supersede anything they or the FDA recommend about the decontamination of respirators.
The co-authors of the study, Steven Chillrud and Belzhan Yan, helped the writers of an informative article published on the Columbia University website, to lay out the steps needed to decontaminate an N95 mask or surgical mask using an oven. These are the steps:
1.Preheat the oven to 170 degrees Fahrenheit. In this case, hotter is not better, because if you surpass this temperature the plastic used to make the masks could melt and affect the fit of the respirator, which is directly linked to its efficacy.
2.After washing your hands, put the mask into a paper bag, always handling it by the straps and never touching the inside or outside of the facepiece. If you’re going to disinfect multiple masks used by different people, use different bags for each one and write the user’s name on them to make sure each person will have the mask that fits them well.
3.Wash your hands again.
4.Fold over the top of the bag three times and place it into an oven bag or a pressure cooker. For these, you’ll need any type of oven-safe and tightly-sealing container, in which you can put multiple bags at the same time.
5.Place the bag or pressure cooker into the oven for 45 minutes, after making sure the oven has finished preheating. It needs to be only 45 minutes, as overcooking the mask could cause it to become damaged, so setting a timer could be useful.
6.After you take out your mask, inspect it to make sure there are no damages to it. This includes holes or tears, as well as checking the straps to make sure they’re still strong.
For more information on this study, you can check this link.