Amazon begins temperature checks and will provide surgical masks at warehouses

The primary purpose of everyone wearing masks is so that people who are asymptomatic or pre-symptomatic minimize the spread of their droplets to everyone else. If the mask also protects you from sick people, that is an added benefit but secondary. Only N95 masks worn properly can guarantee protection for the wearer.

That means covering the mouth is most important because even breathing releases droplets. And the nose should be covered too, but only covering the mouth does help.

[edit after re-reading parent comment]

This article offers some links and data on the effectiveness of even homemade masks at filtering particles:

https://smartairfilters.com/en/blog/diy-homemade-mask-protec...

Ah no any mask decreases the chances of your catching the virus. N95 masks provide complete protection so are important in hospital and health setting. Other masks might not provide 100% protection but if everyone wears them even 50% protection would bring the R to less than 1. People habitually touch their mouth and nose if it is covered they would not do that so that would help as well.

The link you posted is commercial (selling air filters), better to link to the original study from which this is based:

https://www.researchgate.net/publication/258525804_Testing_t...

Liability. Tell people that makeshift masks offer coronavirus protection, and hear the class action lawyers sharpening their quills from a hundred miles. Even if the masks, deployed at scale, help reduce the R factor.

> Only N95 masks worn properly can guarantee protection for the wearer.

"Guaranteed protection" does not matter at all.

Masks that only offer 99% protection are well worth wearing. As are 40% masks.

N95 Masks do not guarantee protection, but they do vastly reduce one's exposure. Simple surgical masks do provide a very minimal level of reduction of droplet intake. Slightly better than nothing, but not far off from bandana-level protection.

Agree that covering the mouth is the most important thing. Hopefully this person just had it down while he was outside and not around others.

Just have employees sign a waiver.

Yea, this is super important to emphasize. Even though surgical and homemade masks are only good at filtering out a portion of the larger respiratory droplets, that's still going to be a lot better than nothing.

This is the same reason the medical authorities have recommended these types of masks for healthcare professionals in areas where N95's are not available. It's better than nothing.

https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/f... (see "HCP use of homemade masks")

From the FDA:

"even a properly fitted N95 respirator does not completely eliminate the risk of illness or death"

https://www.fda.gov/medical-devices/personal-protective-equi...

That's a good point. To complete: Just tell CDC to tell employers to have employees sign a waver.

The 95 in N95 literally means 95%

But 95% of what?

Probably not calibrated on Coronavirus transmission.

Non-oil particles over 0.3 nm, of which droplets containing viruses is one of. There are P100 masks (oil+non-oil) as well, but they're more expensive and harder to breathe through.

Only when worn properly, a 20% mask that you take off with your hands from the front and then don't watch your hands or any other uncareful behavior when using it is going to make more harm than good and for those it would have been better to not wear anything at all.

I can see how touching the mask can lower the protection.

To categorically say it always makes more harm that good seems entirely wrong!