Nano masks are face masks made with nanoparticle fabric, and they have been gaining popularity over the past year. Nanoparticles are ultra-small. Their size is comparable to that of SARS-CoV-2. These particles range in size from 1 to 100 nanometres, which is about ten thousand times smaller than the width of a strand of hair.

Scientists are studying and using nanoparticles in some mask designs because of their potential ability to stop or slow the spread of microorganisms. Antimicrobial products often target these microorganisms which include bacteria, viruses, protozoans, and fungi, including the virus that causes COVID-19.

Researchers have been using nanotechnology for years because of its unique characteristics, including tiny size, adaptability, and multifunctional uses. In recent years, nanomaterials have been used in the prevention, treatment, and diagnosis of diseases. Now experts are hoping technology combined with nanoparticle-based masks can help stop the spread of COVID-19.

Face masks made with nanoparticle fabrics or components can sometimes repel water, improve filtration, and stop microbes from possibly being inhaled or growing on the surface of the mask.

Some of these masks are made with one billion tiny fibers woven in, called nanowhiskers. They help prevent droplets from being absorbed. Some are coated with water-repelling nanoparticle material. Some include nanoscale 3D surfaces. One big aim of most nanoparticle face masks are the smaller gaps that occur between fibers, so particles bigger than 100 nanometers in size may not be able to pass through.

One strategy many researchers have used in mask designs are focused on the surface of masks, including a wide range of nanoparticles and materials:

• copper
• iodine
• silver
• gold
• titanium
• zinc
• other metal and metal oxide materials
• polyamidoamine
• polypropylene
• polyvinylidene fluouride
• nylon resin
• selenium
• various carbon-based antiviral materials
• other inorganic antiviral nanoparticles
• N-halamine
• chitosan
• other sunlight active nanofiber membrane and photodynamic antiviral materials

These materials can be weaved into fibers or embedded in non-woven fabrics of protective face wear. Several studies have shown the potential of these types of masks to inactivate some viruses and help block pathogens from entering through the mask, much like a filter. They may also destroy various pathogens that come into contact with the mask, so contaminating masks are much less likely.

The better the filtration and stronger the antiviral properties of antimicrobial masks, the more effective they may potentially be in stopping the spread of COVID-19. However, every mask is made with different materials which have different properties like durability, stability, chemical makeup, and antimicrobial strength.

Very few nanoparticle masks have sought approval from national medical product regulatory boards and few have undergone rigorous randomized controlled trials to determine if they are safe and effective. In fact, there is potential for medical harm caused by some of these masks, including those with compounds like nano-silver or graphene which can cause over-exposure, inhalation, and damage to multiple organs. Producing and disposing of these masks also pose environmental challenges in addition to their medical risks.

Overall, the potential for nanoparticles in protective gear like face masks is exciting but their safety and efficacy profiles have not been established using a routine strategy or methodology in most countries. Each masks' protective factors and safety for the wearer may vary widely, from dangerous and a breeding ground for microorganisms to an effective method of filtration and virus neutralization. The standards, materials, science, ethics, and processes of each mask-making company may also be quite different in each country. Regulatory standards and agencies might not have the ability to effectively monitor their production or study their abilities. In order to avoid any potential side effects, any face mask people may consider purchasing should be certified by a national or international health and regulatory agency (like the World Health Organization or a ministry of health), and have undergone rigorous, peer-reviewed studies to determine their safety and efficacy. Otherwise, wearing a cloth mask over a surgical mask is still the safest way to stop the spread of COVID-19 through masking for non-health professionals.

Dr. Joseph Nderitu of Kenya recently unveiled a new, reusable surgical mask using what his company calls "antimicrobial fabrics" which they claim are able to kill viruses on contact. The Tiira Medical Services' Nano Mask is the latest in a line of new mask types invented by scientists, physicians, and engineers to kill or neutralize viruses, microbes, and other bacteria. The goal of these masks is to enhance the level of protection already given by masks to further prevent the spread of various illnesses.

Dr. Nderitu noted in the publication Nation that even surgical masks with high levels of filtrations don't filter all microbes, tiny, living things that live in water, soil, and the air and can potentially make us sick, help with our health, or don't really have an impact on us. The most common types of microbes are bacteria, viruses, and fungi.

Tiira's Nano Mask has been tested in two rounds and was then approved by the National Microbiology Reference Laboratory under the Ministry of Health. However, it should be noted that the mask was tested against antibiotics that have potent responses against five common bacteria:

• staphylococcus aureus
• klebsiella pneumoniae
• pseudomonas aeruginosa
• acinetobacter baumannii
• escheria coli

None of these bacteria are the cause of SARS-CoV-2 or COVID-19.

The two tests the Tiira Nano Mask underwent were called the zone of inhibition test and the inoculum absorption test.The first test researched how well the antimicrobial fabric was able to stop the growth of bacteria after it was placed on the fabric on an agar plate in the lab for 24 hours, at a temperature that would allow the bacteria to stay alive.

The second test involved spiking two fabric swatches with test bacteria and then leaving it in a petri dish. The fabric was tested at one, four, and twenty-four hours after first being soaked.

Both of these tests revealed no bacterial growth and were run by a lab overseen by Kenya's Ministry of Health.

These masks have demonstrated the ability to prevent bacterial growth from occurring, but that does not mean they can kill the virus that causes COVID-19. There have been no peer-reviewed publications about the nanoparticle antimicrobial fabric's interactions with SARS-CoV-2, nor has Tiirahealth commented on the mask's impact on COVID-19. Though many articles have come out about this particular mask, their impact on COVID-19 has not been shown.