[petertodd]

Masks that aren't worn correctly tend to have very low efficiencies, because the air just bypasses the mask at the edges. Depends on many factors like the type, how hard you are breathing, etc. But filtering just 20% of the air breathed in is quite possible. And let's face it, people intentionally wear them incorrectly all the time because they suck to wear.

If you and I both have 50% filtration, that's the equivalent of 75% filtration. For the person who is vulnerable, that is much less effective than just wearing a 95% minimum filtration valved N95 mask/respirator properly.

It's just ridiculous that an elderly man on a flight, sitting next to a healthy 15 year old more likely to be killed by a flu infection(1), will be told to take off his valved N95 respirator here in Canada, to protect that 15 year old. I have friends who have seen this happen first hand.

1) https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm