Pertinent Questions

 

Is something better than nothing?

  • Some protection is better than nothing, if you have to go into public anyway (work, purchasing necessities, etc.)
    • Spanish Flu measures, SARS, H1N1
  • Engineering control of having something there to keep you from touching your nose and mouth (and eyes – wear glasses/sunglasses/goggles) with contaminated hands.
  • Helps to keep you from spreading it if you have it already.

Use cases

  • Quick run into a store to obtain necessities. Short period of time in environment with many new contacts. Comfort less important than protection.
  • Work away from home. Comfort more important than protection, though bulkiness concerns will vary with type of work. Hopefully protection is less critical due to physical / social distancing from other people.
  • EMS/fire department medical call to case where COVID-19 or flu symptoms not reported. Comfort less important than protection, but must still be able to work with patient and move relatively freely. Should be able to prepare and don mask in a reasonable amount of time to respond to call.

Commercial masks are made with industrial design (fit/finish), filter media, and sealing that:

  • works out of the box (no preparation by user, long expiry date)
  • is compact (minimal surface area and volume)
    • Filters with higher resistance (requiring more breathing effort) can be enhanced with powered blowers
      • https://www.youtube.com/watch?v=oS6GA83nbds
    • Could materials with uncomfortably high resistance be used if the surface area of filter is increased? Could a large ball or box of filter material on your back attached to a hose work?
  • is easy to don with a reliable seal
  • has low air resistance filter media (allowing for comfortable medium to long term wear)
  • is reliable for intended use in high-risk settings
    • N95 blocks 95% of 0.3 um particles
    • N95 can generally block most 90-100% of particles that are the size of respiratory droplets (0.3 um to 10 um)
    • high quality control levels / low failure rates
      • If it says “N95” on the package, there is ideally a low (maybe 0.0001%) chance that any one mask will fail to meet the standard.

The above design criteria for commercial masks is not a necessity for homemade masks that meet the aforementioned civilian use cases.

  • some user preparation okay. may not need to last years in storage ready to go.
  • okay to be bulky and cumbersome (large intake to make up for high resistance)
  • okay if you need help to put it on. some seal is better than nothing.
  • breathing through heavier material okay for short period of time (e.g. running in and out of the post office or a store)
  • it is higher risk to have nothing at all, which is your next best alternative