Just a few gaps in a face mask can reduce filtration efficiency by 50 percent, a new study found, after simulating the effect of gaps by drilling holes into various material-combinations commonly used to make face masks for consumer use. The good news: several U.S. researchers have reported on cloth fabric combinations that are good at filtering particles--as long there's no gaps. Moreover, a free reference guide on basic standards for consumer face masks has been made available June 17 by the EU. The guide ensures breathe ability and good filtration via minimum requirements and testing methods for making quality consumer face masks. The EU defines "consumer or community face masks" as not included in the scope of of personal protective equipment (PPE) and medical devices (MD) that have long been regulated both in the EU and the US.
If your still not convinced these invisible droplets exist, scroll down on the ScienceNewsService.com home page to see the NIH video showing how strong laser-technology lights up speech droplets like an invisible fireworks display. And see the SNS YouTube video about the tipping point where droplet size transitions from temporarily airborne to saliva-size that falls flat here.
People worldwide, including the U.S. National Guard, have been hand-making face masks to slow the pandemic.
Photo Credit: Rhode Island National Guardsmen sew face masks to ensure guardsmen had the masks required to slow the spread of COVID-19 and protect the force. Photo Credit: Army National Guard PFC David Connors.
So now hopefully you've seen the video lighting up invisible, airborne, particles that spray during speech, and you've seen both top fabric-layer-combinations reported in U.S. studies as well as combinations that fail breathability test in the EU. Now, there's the "no-gap" challenge to deal with. Here, five ways to lose gaps and increase the filtration efficacy:
1) If you are starting from scratch to make or buy a cloth face mask, review any of the many patterns provided free from talented YouTube communities, Choose a patterns that takes into consideration a nice sealed fit all the way around. Don't know where to start? Try the ScienceNewsService.com YouTubeChannel.
2) Once you’ve made or bought a mask for yourself or your kids, try the mask on inside out and check the fit all the way around for gaps. If you see a gap, pinch it at the edge. Mark with a pencil where the cloth meets between your pinched fingers, or have someone help you take it off while still pinching. Take straight pins and pin the area that needs to be tightened—this will become your “dart.” You will now have a little slanted line to sew, much like the side of a large piece of candy corn depending on the size of your gap. You might want to try the mask back on after pin fitting, but before sewing your dart. See the SNS Science News Service YouTube video on what this dart looks like if you've never seen one. Alternatively, a good seamstress or experienced sewer can easily pin fit your darts while you are wearing the mask.
3) Perhaps you’ve still got some gaps on either side of the bridge of your nose. Depending upon the design of your mask, you may still be able to install a “nose grip” or “nose pinch”. There are many great suggestions and how to's on YouTube for a variety of materials to use for making and installing nose pinches. Some favor coated picture-frame wire. The wire has a nice protective plastic coating and comes in different thicknesses. You will want a 4-inch total bendable strip, which can easily be doubled and tripled up and so forth until you get the strength that works best for you. Now, cut out a piece of fabric, lay down your mask and sew or base stich the wire into the mask up near the bridge of the nose. If you are concerned about poking air holes in your mask, consider method number four below.
4) Try making home-made “gaskets” to fill in gaps around the edges of your face mask and at the nose bridge. These might be made by sewing inch-sized pieces of high-filtration fabrics while bunched up, creating a ruffled effect. Your basically creating a bit of bulk with friction to stuff inside the two gaps. Try making the gaskets out of the best performing fabric combinations tested in the filtration efficiency (FE) study by the U. of Chicago and National Argonne Lab scientists. To see the defined content of these fabrics, go to ScienceNewsService.com under SNS content or the blog and see charts provided.
5) Use the sizing dimensions and patterns provided free by the EU on June 17. The new reference guide provides adult face and head size dimensions that are illustrated to aid in achieving a proper fit. Children’s sizing is provided in three age categories and also are illustrated to aid in achieving a proper fit. “A community face covering that hinders the user's ability to breathe when first put on is deemed unsuitable. The user should be aware that it can take time to become comfortable with the community face covering,” explains the EU reference guide. Remember, the worse filtering mask is the one so unbreathable, so uncormfortable, it is taken off while still out in public. A link to the initiative’s document referencing minimum performance requirements and testing for washable material-based consumer face masks intended for the general public—whether homemade or mass-produced—is free and can be downloaded at: ftp://ftp.cencenelec.eu/EN/ResearchInnovation/CWA/CWA17553_2020.pdf
Thanks for reading about science that informs consumer face mask quality and safety--when you stay safe, others stay safer.