Far from being a spark plug for crowd trouble, I believe anthems, whether booed or sung with lung-busting gusto, add to the atmosphere of the game and put fire in players' bellies.
BBC: SPORT | Football | African | To sing or not to sing
2.
The U.S. Environmental Protection Agency has singled out the greater Salt Lake region as having the nation's worst air for much of January, when an icy fog smothers mountain valleys for days or weeks at a time and traps lung-busting soot.
NPR: Sickening Fog Settles Over Salt Lake City Area