Experts at Penn State University say the answer is simple: when the undesirable qualities outweigh the good qualities.

VOA: special.2011.07.26

Experts say these simple steps can prevent the health problems linked to heat.

VOA: special.2010.07.27

They should have some courage, and they should stop it. It is no good for the players, and somehow I hope the players have the ability around the world to stand up and say we are not playing on this, plain and simple."

VOA: standard.2009.06.07