Update March 4
I've done an extensive analysis of the disease and Impact of a Pandemic.
I'll excerpt my On Masks Section as I suspect the reasoning contained within will be the most appropriate and interesting to this thread. But there is good stuff throughout, I've built things for lay readability, and am not a technical expert, I would appreciate thoughts and advice. I don't have variables for mask exposure, but I think my reasoning is solid and useful. You can tweet me @qastokes
About N95 Masks
All non-N95 face masks, such as medical masks, (of the dental kind), are relatively useless for self-protection, as they lack a seal. Please donate your excess to medical facilities. These are very useful for containing the spreading of all illness, those who are sick and coughing, regardless of disease, should find and wear these type masks. Containing spread is far more effective than reducing exposure for managing the risks.
Please understand N95 isn't prevention, it's odds increase. When properly fitted and used it reduces exposure, but technically it's only 95% efficient.
An N95 might keep a doctor with constant exposure alive, but won't help Joe who's out shopping much. Wearing a mask could theoretically increase your risk if used wrong, by being a capture of virus that moves along with you and extends your exposure time. It is not generally helpful, compared with handwashing and effective prevention protocols.
It is true there is benefit to be had by using a mask. But it is only significant if you are competent in following the use protocol. It is better by far to learn & to carefully follow all the other higher impact protocols, especially handwashing. By far the greater benefit, for you individually considering your total exposure risk across time regarding the disease and it's spread, around you to managing your personal exposure will be for those managing the disease directly to have the best protection they can. Hence my advice to donate extra masks to those at highest risk.
Think about this along the lines of "the more the disease spreads, the greater your total exposure risk, regardless of managing your personal exposure risks."
Note: For really significant improvement in your exposure chances, I & wearing a mask effectively, you will need to carefully follow the behavior protocol for a disposable full body exposure management system. A protocol which includes gloves, a hooded tyvek particulate suit, and goggles, along with the mask, this is only really applicable in an extremely exposing environment. Additionally, a P100 would be the optimal mask of choice for this situation and protocol.
The biggest risk management benefit comes from one complete set of masks and a full body exposure management system for every one of your loved ones. This allows you the freedom to make one situation optimizing decision in a worst case scenario.
This would look like:
The family is out of food. Healthcare is overburdened to the point the death rate has matched the critical cases rate. You must move with high risk of high exposure.
Alternately, with planning these suits can also be burned one use at a time in a clean room caring for a loved one, allowing for several days of constant and very direct care with low gain viral load & exposure risk for those still without symptoms or as yet uninfected.
Note for completeness: of all the routine contexts to wear a mask, high droplet spray environments are the ones the mask will help in the most, especially if you sanitize your clothes afterwords. I would strongly consider wearing one in a crowded subway, if there is a known outbreak in your city. This would only significantly help if you wear the mask correctly, sanitize clothes, & don't touch your face and are meticulous about hand washing.
Note: In the summary post, this comment thread suggests getting only normal amounts of vitamin D.