9 abril 2015
Researchers say that levels of radon in Pennsylvania homes – where 42 percent of readings surpass what the U.S. government considers safe – have been on the rise since 2004, around the time that the fracking industry began drilling natural gas wells in the state.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/6e-jASAVeek/150409081321.htm
