face mask chemistry

The Science Behind Face Masks

With the emergence of the COVID-19 pandemic, doctors and scientists have debated back and forth about the effectiveness of face masks.

After months of societal guinea-pigging, and even more importantly, dedicated research, the majority of scientists have concluded face masks work. The U.S. Centers for Disease Control and Prevention (CDC) recommends citizens wear face masks to prevent the spread of the novel coronavirus.

But, do cloth masks really work? Or should people choose medical masks when given the choice?  The truth is, some materials make for better masks than others. Let’s look at the research to find out what the science says.

Infectious Disease vs. The Homemade Mask

In 2013, Cambridge University in the UK conducted a study analyzing the effectiveness of homemade cloth masks.

Researchers looked at how several common materials performed in comparison to surgical masks. Materials analyzed included:

  • Cotton t-shirt
  • Scarf
  • Tea towel
  • Pillowcase
  • Antimicrobial pillowcase
  • Vacuum cleaner bag
  • Linen
  • Silk
  • Mix of cotton

Researchers analyzed the efficiency of filtration and the pressure drop, looking at the performance of a single and a double layer of the material.

Test subjects created their own masks based on the surgical mask design. They were then fit-tested to ensure they worked well. Finally, the masks were sprayed with a few organisms in a size comparable to the influenza virus.

Then, filtration efficiency tests were conducted to see how well the masks filtered out the organisms. Measurements of pressure drop across the fabric showed that a poor mask material could still provide proficient filtration.

One of the findings of the study was that attempting to breathe through some of the materials was so difficult that most of the air test subjects inhaled came in from the edges of the masks rather than through the material itself.

After the study, researchers concluded the 100% cotton t-shirt and the pillowcase were the most effective household materials for an improvised face mask. The found doubling the layers was counterproductive, making it difficult to breathe.

However, the study clearly revealed that when choosing between a surgical mask and a homemade mask, the surgical mask is a much better choice.

The N95 Tops Them All

While the study found that surgical masks are much more effective, there are various types of protective masks. Protective masks come in different grades, offering different levels of filtration.

When referring to a surgical mask, the most common is the N95 mask. This type of mask meets a filtering level of FFP2 (Free Flight Phase 2) or FFP3. This rating looks at how well a mask can handle hazardous material.  However, to guard against diseases such as influenza, a more accurate measuring grade is needed, such as the PFE (Submicron Particle Filtration Efficiency rating). N95 masks have a PFE of 99.9% for every 0.1 micron particles, which is a great rating. There is also another rating called BFE (Bacterial Filtration Efficiency) which looks at how well a mask filters aerosol particles of 3 microns in size.

A study on SARS (Severe Acute Respiratory Syndrome), another coronavirus, found N95 masks to be highly effective at preventing the spread of the virus.

Any Mask is Better than No Mask

Overall, research shows time and time again that masks work. When it comes to which mask to choose, the best choice is the N95.

However, a 2009 study found that even poorly fitting medical masks were found to interrupt viruses and airborne particles, even when someone sneezes.   But, when you don’t have access to either N95 masks or other medical masks, a makeshift mask made from a t-shirt or pillowcase can still help.

For more information on how Noah Chemicals products can compliment your project, reach out to one of our full-time chemists today.

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