Face masks and battle against Coronavirus

Are face masks effective in the battle against the spread of the Coronavirus virus?
Many governments now seem to think so and are making the warring of them a requirement of any departure from the confines of one’s home.
The Chinese government are so convinced as to their effectiveness (and concerned for their nationals living overseas) that it has posted a supply to every citizen. The sheer scale of contacting every Chinese person wherever they are in the world is unbelievable.
In the U.K. we find it difficult to source enough face masks for those in key services yet alone provide them for the populous. Could it be that if we were to concede to the growing opinion that face masks were an effective tool in the battle against the spread of the virus, the demand for them would make it even more difficult to obtain the necessary supples for our key workers?