Consideration in choosing a mask include Bacterial filtration efficiency, sub-micron (e.g., virus) particle filtration, resistance to fluid/ blood, breathability and cost.
Viruses are much smaller than bacteria. Corona viruses are very small viruses. An N-95 mask is best for filtration when one is dealing closely with the virus. The virus is carried in mucous and thus the mask should be fluid resistant. Unfortunately, the better a mask filters, the harder it is to breathe when using that mask. And the N-95 masks are more expensive. But you can always find cheaper N95 masks for sale online.
Do you want to trade comfort and cost for safety? I cannot answer that question for you. If you are a nurse working with pandemic patients, you will want the N-95. If you are riding a bus or taking a walk, you may compromise.
N-95 Mask is the ultimate mask but not always easy to breathe. Fluid resistant and at least 95% efficient against solid and liquid particles larger than .03 microns, excluding those containing oil. (The “N” stands for Not oil proof) The N-95 or higher is a best choice if one expects to be exposed to the virus. The fit is important so that there are no leaks between the mask and face.
Consider smaller sizes for children. A ” Duck-Billed” shape N-95 is available that allows extra breathing room for the face and nose.
Not to be relied upon are simple dust masks and procedure masks not meeting these fluid resistant and filtration standards. Most are not fluid resistant nor do they filter the virus.