The Most Effective DIY Masks for the Coronavirus


SUMMARY POINTS

  • N95 masks meets CDC requirements & blocks about 95 percent of particles that are 0.3 microns in size or larger
  • CDC guidelines for protection against common viruses, as well as the most foreseeable bioweaponry, ranges in size from 1.0 to 5.0 microns
  • Current coronavirus is just 0.1 microns – three times smaller- therefore N95 masks are less effective 
  • Typical surgical mask is 89% effective against .02 micron particles or smaller
  • Vacuum cleaner filter is 86% effective for .02 micron particles or smaller
  • However, masks must allow breathability, which many household materials prevent
  • Therefore, researchers concluded that cotton t-shirts and pillowcases are the best choices for DIY masks.

What Makes the N95 Mask Special?

The “N95” is a government efficiency rating that means the mask blocks about 95 percent of particles that are 0.3 microns in size or larger.

The N95 rating meets the Centers for Disease Control and Prevention guidelines for protection against tuberculosis and anthrax spores, as well as the most foreseeable bioweaponry, which ranges in size from 1.0 to 5.0 microns.

So, the N95s are more than capable of preventing their inhalation.

What Household Material is Effective for Filtration?

Researchers at Cambridge University tested a wide range of household materials for homemade masks from common household supplies. To measure effectiveness, they shot Bacillus atrophaeus bacteria (0.93-1.25 microns) and Bacteriophage MS virus (0.023 microns in size) at different household materials.

Below is what their research found:

As expected, the surgical mask performed best, capturing 97% of the 1-micron bacteria. Yet every single material filtered out at least 50% of particles. The top performers were the vacuum cleaner bag (95%), the dish cloth (83%), the cotton blend shirt fabric (74%), and the 100% cotton shirt (69%).

Typically, coffee filters are made up of filaments approximately 20 micrometres wide, which allow particles through that are less than approximately 10 to 15 micrometres. There is not testing available to measure their effectiveness.

What is the size of COVID-19 Particles?

The test above used bacteria that were 1 micron large, yet the coronavirus is just 0.1 microns – ten times smaller. Can homemade masks capture smaller virus particles? To answer this question, the scientists tested 0.02 micron Bacteriophage MS2 particles (5 times smaller than the coronavirus).

Are Two-Layered DIY Masks More Effective?

Would the masks work better if we doubled up with two layers of fabric or filters? The scientists tested virus-size particles against double-layered versions of the dish towel, pillowcase, and 100% cotton shirt fabrics.

Overall, the double layers didn’t help much. The double-layer pillowcase captured 1% more particles, and the double-layer shirt captured just 2% more particles. Yet the extra dish cloth layer boosted performance by 14%. That boost made the tea towel as effective as the surgical mask.

Why the Best DIY Masks are Not from Vacuum Filters

Researcher continue to suggest I pillowcase and the 100% cotton t-shirt are the best materials for DIY masks. Why?

A protective mask must also allow breathability, which is a critical factor for busy healthcare workers. The reality is comfort will influence how long you can wear your mask.

Therefore, researchers tested the pressure drop across each type of fabric. This gives us a good indication of how easy it is to breathe through each material. As a benchmark, they compared breathability of each DIY mask material to the surgical mask.

Researcher Suggestion for DIY Masks

Based on particle capture, comfort and breathability, the researchers concluded that cotton t-shirts and pillowcases are the best choices for DIY masks.

READ SCIENCE BEHOND N95 FILTER

Tutorial Video to Make DIY Masks

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