I've seen announcements from the police telling people not to use hazard lights in fog. While that might not make it illegal (I confess I don't know if it is or not, I used the word in my comment above to sensationalise), it's what the police advise. The fact that some of them don't follow this advice themselves is irrelevant, and just indicative how the police drive generally.

The root problem is that many (most?) cars here don't have fog lights, which is absolutely ridiculous, but I can't see Qatar changing their car import laws to rectify this.

But despite this, it's still very dangerous to drive with your hazard lights on even if you don't have fog lights, for the reasons explained already.

adeel was saying that to indicate that you are going to turn left or right you should turn off your hazards and then use the indicators as normal. Most people don't indicate when they're turning in normal weather, so I can't see them doing this really!!!