From what I’ve been reading, the bolide exploded at about 30,000 feet up.
It’s a damn good thing it exploded as high up as it did. The damage caused by the pressure wave was significant. I can only imagine how much worse it would’ve been if it had air-burst at 3,000 or 5,000 feet above Chelyabinsk - it would’ve been like a nuclear blast.
Still, over 950 injured (mostly minor) and structural damage to some 3,000 buildings. That’s nothing to sneeze at. It’s quite similar in many ways to the 1908 Tunguska Event.
I counted 27 seconds in one of the videos from the bright blast to the occurrence of the shockwave. At 1100 feet per second, that's roughly 29,700 feet.
Others have pointed out a good lesson here. If you witness a blindingly bright flash in the sky, you probably have about less than half a minute to take cover to avoid injury from the blast. One must avoid the temptation to stand at the windows to admire the view. For those with a strong sense of scientific curiousity, it's a challenge.