Below are the links and excerpts of the articles I found:
Can masks help stop flu spread?
The Department of Health has focused on getting what are known as respirator masks. These have filters, which stop a person breathing in some particles in the air. They are much more effective than the standard surgical masks or dust masks that are sometimes used by builders.
However, none of the masks can stop 100% of the particles getting through and become less effective once they become moist. Instead, they are better at stopping the virus getting out. Masks alone will not prevent spread of the influenza virus and basic hygiene measures like hand washing, safe use and disposal of tissues and cleaning of environmental surfaces are key to preventing infection transmission.
Can a Mask Prevent Swine Flu?
Sure, if someone is coughing or sneezing in your face, a mask might help. Also, if you know that you're going to be around someone with swine flu, such as a loved one, a mask might be warranted. But otherwise, that’s not the most effective strategy for preventing swine flu because you don't catch most respiratory viruses from people coughing in your face.
Here's what generally happens. Someone with a virus sneezes or coughs in their hand. Then, they touch something like an elevator button or a doorknob. You come along a few minutes later and touch that same button or knob. Then, without thinking about it, you touch your face – your mouth, nose, or eyes – and the virus takes hold of you.
As mundane as it sounds, the most effective way to prevent getting respiratory viruses like swine flu is washing your hands. But most of us don’t do it often enough and don’t do it the right way.
In summary, I think using face masks will help you from spreading your virus to others when you sneeze / cough, but I guess, most important is for ourselves to keep ourselves clean and maintain good and proper hygiene. What's the point of wearing the mask if you don't keep yourself and your surrounding clean?