Why?

Why do Korean road-cyclists hide themselves behind these obscure masks? It's not their religion I suppose. It cannot be the weather, that's fine. Nice temperature, no wind, nothing. It seems that you cannot ride a road bike here without this awkward disguise.
Some say that many Koreans don't like a dark tan and that's why they cover the skin. I consider the price very high, free breathing is pretty important when delivering a physical effort like cycling.