EMERYVILLE, CA – MARCH 06: A view of cellular communication towers on March 6, 2014 in Emeryville, California. The U.S. Labor Department is asking mobile phone providers to increase safety training for crews who perform work on cell tower sites in the United States. According to the Occupational Safety and Health Administration (OSHA), more tower site workers died in 2013 than in the previous two years combined and four workers have died in the first weeks of 2014. (Photo by Justin Sullivan/Getty Images)