The face masks aren’t especially effective for this disease
Surgical masks protect other people from your coughing / breathing -- they do nothing for you.
N95 masks are notoriously difficult to actually fit correctly. A mask with a filter needs to be completely sealed around your face. You should not be able to get any airflow in from the sides. The elastic is usually too weak, the masks themselves are too lightweight, and they rarely have anything but paper touching your face, so you're not going to be able to get any sort of seal with them.
The only mask that has any hope of protecting the wearer against inhaling airborne particles is a 3M-style cartridge respirator that's fitted properly. The mask should be heavy, the part around your face should be silicone or rubber, and you should be sweating enough to lubricate the mask so that it acts like a suction cup around your face.
But the mandate to wear masks in crowded public places is to protect others from the wearer. Note there have been few if any reported cases of transmission on long flights from China. This may have something to do with mask wearing by carriers of the disease.
1. Not infect others during the period while they feel fine but are actually spreading the virus
2. As a more effective means of preventing spread via coughing and sneezing.
Let's be realistic here -- when the public is in a panic, their behavior gets worse, not better.
agree people should not deceive themselves, however.
A regular surgical face mask doesn't protect.
A more specialized mask, known as an N95 respirator, can protect against the new coronavirus, also called 2019-nCoV. The respirator is thicker than a surgical mask
Edit: For the unfamiliar N95 is a NIOSH standard that dictates the percentage of particulates that are filtered and if the filter is rated for environments with presence of oil. The letter which can be N, R, or P tells you if the filter is good in the presence of oil. N=Not Oil Rated, R=Oil Resistant, P=Oil Proof. The number following the letter tells you the percentage of particulates filtered and typically come in 95, 99, or 100. Both surgical style masks and respirators can be N95 rated.
Then you have P95, P99 and P100 that look exactly the same but also work against oil-based aerosols (e.g. if you're spraying paint). These are frequently what you get from a hardware store.
Now all these are actually filtration efficiency classes. So you can get a P100 mask that looks like this [1] or one that looks like this [2]. Obviously [2] gives better protection, even though they are the same class.
[1] https://www.amazon.com/3M-P100-Disposable-Particulate-Respir...
[2] https://www.amazon.com/3M-Respirator-Reusable-Particulate-Re...
For the big full face or half face respirators, you can also get rectangular multi-gas filters (e.g. for organic vapors, acid gases etc) that you can also get pink rectangular aerosol filters for.
Edit: forgot to mention that all these are US NIOSH class numbers. In Europe you'll find mostly-equivalent ratings to P95/P99/P100 specified as P1/P2/P3 (or FFP1 etc.).
> We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections.
That it didn't find a difference between N95 and plain surgical masks isn't surprising:
> Participants in clinical studies were health care workers in a health care setting. We defined health care worker as any worker in a health care setting who might be exposed to a patient with an acute respiratory infection. [...] Acute respiratory infections may have been acquired during the study from community exposures rather than nosocomial exposure.
It's not obvious (and wasn't discussed) that such a broad definition of 'health care workers' identifies people who are exposed to categorically more respiratory infections than, say, elementary school teachers. Indeed, one of the studies was actually halted due to the H1N1 outbreak in 2009.
So... of the people in the study who did get sick, we don't know how many of them caught it from their kids at home or on the bus to work when they weren't wearing .
Interestingly, one of the two randomized studies they looked at, having by far with the largest number of participants (1669), concludes:
> Continuous use of N95 respirators was more efficacious against CRI than intermittent use of N95 or medical masks.
(The other study with 1441 participants concludes that N95 respirators are more effective in preventing multiple simultaneous infections.)