The BBC just answered a question I often find myself asking: how dangerous is firing a gun into the air? The answer, apparently, is “fairly dangerous”. It seems obvious that if you fire a bullet into the air it will come down to land somewhere. And research from 1962, quoted by the BBC, shows falling bullets can reach a terminal velocity of 300 feet per second, 100 feet per second more than is required to penetrate a human skull. In populous areas where a lot of this celebratory gun-firing seems to take place, the chances of falling munitions hitting the unsuspecting must be quite real and often presumably fatal.
The BBC cites a number of cases of known deaths; for example, these:

When the Iraqi football team defeated Vietnam in 2007’s Asia Cup, three people were killed in Baghdad amid widespread gunshots as fans celebrated. Celebratory gunfire in Kuwait after the end of the Gulf War in 1991 was blamed for 20 deaths.

So now I know and it doesn’t make watching the celebrations in Tripoli any easier. I just watched BBC footage of a man firing off anti-aircraft rounds into the air to mark the liberation of the city (the firing happens at about 2.02 minutes in). Someone somewhere probably regrets that he chose to show his enthusiasm in quite that way.

Update: Another article in today’s Guardian has more on the subject. If you are shot in a regular way your chance of death is between 2% and 6%, according to the article. If a falling bullet lands on you it is closer to one third. There you go.