Fans do not attend Major League Baseball games to enhance their physical health. Among their customary activities are eating hot dogs, drinking beer or sugary soda, sitting idly for hours on end and stressing terribly about inconsequential events on the field of play. But this season, those at Wrigley Field and U.S. Cellular Field will have to forgo one vice. Chicago recently became the fourth city to outlaw smokeless tobacco in sports stadiums (followed shortly by New York). The law owes much to the Campaign for Tobacco-Free Kids, whose president, Matthew Myers, says, "Our national pastime should be about promoting...