I am seeing ads for N95 masks marked "not medical grade".
Generally, that just means they have not been lab tested/confirmed. They aren't necessarily any less effective at filtration than a medical grade one.
Plus I am seeing studies showing wearing a mask can actually hurt more than help
In some cases, yes. The biggest factor probably being a "false sense of security", where users of cloth/paper masks think they are risk-free or over-estimate how effective they are. Other factors: re-wearing contaminated masks that are not clean, more touching of the face with unclean hands to constantly adjust the mask, accidentally wearing them "inside out" when not clean.
and increases the risk of hypoxia.
Yep, I addressed that as a reason that not everyone can wear a mask.
50 K or so deaths from the flu would warrant wearing one.
It can, yes. In a healthcare setting, absolutely. And it is not uncommon in peak normal flu season for healthcare workers to isolate and use masks. In a setting where you are a high-risk person and will be near others possibly affected, it is advisable. The novel flu virus that causes COVID-19 is more dangerous because it spreads more easily, can cause more severe symptoms in some people, and is novel with no vaccine for it (so the population has very little natural immunity to it, yet). So it makes sense to use more precautions than with non-novel flu, including simple masks.
N95 masks are a different story. Those have almost no place in the general population use. They are very restrictive, in short supply, are not effective if not properly fitted, offer no better protection for typical/casual exposure for the flu, and probably don't reduce droplet spread any better than just simple (paper/cloth) masks. It is "overkill", except for front-line healthcare workers.
Since droplet is one of the primary transmission vectors of all flu (of which COVID-19 is a member), simple masks (paper/cloth) can be effective at helping to prevent the spread. This doesn't mean I support the general "orders"/"laws" that require using "a mask" anytime you are outside your home. They are appropriate for when you can't social-distance and should be encouraged. As you probably already know, I strongly support civil liberties and individual rights. The government can and should:
* Educate
* Warn
* Study
* Collect and provide statistics
* Help to organize and distribute emergency containment supplies and gear
* Set guidelines for government workers
Those should be more than sufficient in this matter. Social pressure can/will do the rest. But "ordering" people around does not mesh with a free society. Neither does turning non-users into criminals or encouraging neighbors to "spy" on you and "report you to authorities." The legal authority to do so is dubious, at best. It sets a bad precedent. And it can [and usually does] backfire by creating resentment and conflict. Life is complicated and individuals need the ability to make their own decisions based on their own risk assessments. Just like riding a motorcycle
