Throughout the year, due to the pandemic being the most prominent threat the world faced, N95 masks became known to most people who previously had never heard of this term. They’re used in healthcare settings for virus protection, as they can effectively filter out the SARS-CoV-2, the virus responsible for COVID-19.
This has made them incredibly valuable, which has resulted in shortages affecting not only them but other medical supplies as well, making them difficult to find for sale in physical or online stores.
Big companies like 3M and Honeywell have worked all year to increase the production of all these items, including N95 masks, with some of the most popular models being the 3M 1860, 3M 8210, and 3M 8511. However, the demand has been so high the production still isn’t able to prevent the shortages.
Some experts believe this is because of the scarcity of some raw materials and the complexity of the production of these masks. Today, we’ll briefly explain how N95 respirators work and how they’re manufactured.
Understanding how N95 masks work and why they’re important
N95 masks are specific types of disposable face masks used at the moment for virus protection in situations where exposure to the virus is very high. They’ve been considered, for this reason, the best option for healthcare workers since they’re some of the workers who are exposed to the coronavirus most closely and consistently.
Their name comes from a classification used in the United States to regulate respirators. It’s established by the Centers for Disease Control and Prevention (CDC) through the National Institution for Occupational Safety and Health (NIOSH), the federal agency in charge of making recommendations to ensure safe workplaces around the USA.
NIOSH gets sent to all respirators manufactured with the intention to be marketed as N95. After testing them out, they can certify whether or not the respirator meets the criteria to be considered an N95 mask, so their approval is one of the most important parts of the manufacturing process. Additionally, the Food and Drug Administration (FDA) regulates the N95 masks that are manufactured to be medical equipment.
To be considered an N95 respirator, the mask must have two main characteristics: to be non-oil-resistant and to have a filtration efficacy of 95% for airborne particles (those with a size of 0.3 microns). Particles that are airborne and non-oil based ae very diverse and can be found in a wide variety of work settings, which is why N95 masks can have multiple uses. Some of these particles include smoke, dust, pollen, and viruses like the flu or the coronavirus, among others.
How are N95 masks manufacturers?
To be completely effective for filtration, N95 masks contain multiple layers of a filtering media called non-woven fabric. This material is usually made out of polypropylene, although other plastics can be used. The layers are two superficial ones, covering the inside and outside of the mask, a pre-filtering layer and a filtering one.
The superficial layers, which are the mask’s main protection against the environment, are made through spun bonding, a process in which melted threads of polypropylene are blown into a conveyor belt with some nozzles. The diameters of the fibers in these layers will be 15 to 35 micrometers, and they bond together through thermal, mechanical, or chemical techniques, building a cloth.
The pre-filtering and filtering layers are placed between the superficial layers. The pre-filtering one is made with “hot calendaring” techniques, in which plastic fibers are run through rolls with high pressure and heat, which bonds the fibers together thermally.
Then, the fabric is needle-punched by sending barbed needles through it repeatedly, which hooks them together and increases its cohesiveness. This layer is very stiff and thick, which allows the manufacturer to mold it into any shape desired, and this is why this layer makes up the shape of the respirator.
Lastly, the filtering layer is made through melt-blowing, a process similar to spun-bonding but threads have a diameter much smaller than a micrometer, and they bond together by themselves as they cool down. The resulting material is known as a “high-efficiency melt-blown electret (or polarized) non-woven material.”
After making each layer, they’re combined through ultrasonic welding, and then the additional pieces like the straps or metal strips are added. Before being packaged, the respirators are sterilized.
Before being distributed and sold, as we mentioned earlier, the masks need to pass the tests made by NIOSH. Before NIOSH tests them, they must be conditioned for 24 hours in a place with a temperature of 38 degrees Celsius and a humidity level of 85%. Then they perform a set of tests among which the most important ones include particle penetration, particle saturation, and breathing resistance.
We also mentioned that the FDA regulates N95 masks intended to be used as medical equipment, performing tests such as fluid resistance, biocompatibility, flammability, and particulate filtration.
This article has more in-depth information about the process of manufacturing N95 masks.
The majority of the medical supplies needed right now, including N95 masks, KN95 masks, surgical masks, gloves, gowns, and face shields, are scarce items right now that are extremely necessary in healthcare facilities.
They’re currently being prioritized for their use by frontline workers, which is why the CDC urges the general public to wear other alternatives, like the reusable cloth masks that are widely available for sale and people can buy them in bulk and wholesale online. They come in multiple sizes, so kids over the age of 2 can wear them too.