For the last 10 months, one American company in particular has been the main manufacturer of medical supplies and personal protective equipment (PPE) not only inside the United States but around the world. They’ve been doing incredible work to increase the production of these extremely necessary items, and N95 masks in particular have been highly requested and hard to find.
In this article, we’ll talk about the process for manufacturing these effective face masks, as well as who 3M is and what they have done during the pandemic to help out. Finally, we’ll explain why the N95 mask is so important right now.
The process for manufacturing N95 masks
For a single N95 mask, multiple layers of non-woven material are needed. All of them serve a different purpose and are made a little differently, but they’re made with the same raw material, which is plastic, and the most commonly used one is polypropylene. The layers are two superficial ones, a pre-filtering and a filtering layer.
The first two layers, the superficial ones on the outside and inside of the mask, act as the mask’s main protection against the environment. These are made with a technique called spun bonding, in which the melted polypropylene threads are blown into a conveyor forming fibers with a diameter of 15 to 35 micrometers in size. There, the fibers are bonded with techniques that can be either mechanical, thermal, or chemical, until a cloth is formed.
The pre-filtering layer is made with a combination of two processes. First, plastic fibers are put through high-pressure rolls which are also heated, which bonds them together forming the fabric. Then, barbed needles are sent through this fabric multiple times, which hooks the layers together. This needle-punching technique allows more cohesiveness to this layer, and the result is a thick and stiff material that can be easily molded into any shape. For this reason, this layer makes up the shape of the mask.
The most internal layer is the filtering one, and the process to make it is called melt-blowing, which is very similar to spun bonding. Multiple nozzles spray melted plastic threads into a conveyor using air, but the resulting fibers have a much smaller diameter of less than a micrometer. When they cool down, they bond together to create the fabric, which is called a “high-efficiency melt-blown electret non-woven fabric.”
Once the layers are created, they’re combined by ultrasonic welding, and then accessories like the straps or the metal strips on the nose area are added. Finally, when the mask is completed, it’s sterilized.
Before being marketed and distributed as an N95 mask, an institution in the USA has the responsibility to perform some tests and make sure the mask meets the criteria for that respirator type. This entity is commonly referred to as NIOSH, and we’ll talk more about them later.
The process of testing is explained in detail on the CDC website, but in general, these masks are put through multiple tests. Before this, they’re conditioned for 24 hours in which they’re kept at a temperature of 38 degrees Celsius and 85% humidity levels. The most important tests NIOSH performs are breathing resistance, saturation, and particle penetration.
Additionally, the FDA might have to regulate the mask as well if they’re going to be used as a piece of medical equipment, like the 3M 1860 mask model, which is a surgical N95 mask. Other 3M N95 masks, like the 3m 8210 and 3M 8511, only need the NIOSH certification. They perform another set of tests, including biocompatibility, flammability, particle filtration, and fluid resistance.
For more information about this process, click this link.
The importance of N95 masks during the pandemic
N95 respirators have been considered the best face mask for healthcare centers during the pandemic, as they offer much more virus protection than any other reusable or disposable face mask available. Their antiviral properties are much higher than surgical masks, which are the most widely used face mask in healthcare settings, but don’t have a very efficient ability to filter out viruses, which is why the N95 mask is the preferred choice in high-risk situations.
The name of the masks comes from a classification and naming system for respirators established by the National Institute for Occupational Safety and Health, also known as NIOSH. As we mentioned, this entity regulates respirators in the USA. According to them, the name N95 means that the respirator isn’t resistant to oil, which is what the ‘N’ means, and that it has a percentage of minimum particulate filtration efficacy of 95%.
This means these masks can only filter out airborne particles, which are those with a size as small as 0.3 micrometers, if they don’t contain oil, and they do so with an efficacy of 95%. Examples of such particles include not only viruses like the flu virus or the new coronavirus, but also others like dust, smoke, and pollen, which is why these masks can have multiple uses.
These masks, along with other important medical supplies and PPE, including face shields, surgical masks, KN95 masks, gloves, and gowns, have been extremely scarce during the last 10 months due to the increase in their demand as a result of the pandemic. They’re very difficult to find for sale even online, and healthcare settings can’t buy them in bulk and wholesale as they need to.
To make sure all these items are reaching healthcare centers, the CDC recommends the use of cloth masks by the general public, including kids over the age of 2 years old, as they’re considered enough when used in low-risk settings in combination with social distancing.