Sand dust created from the hydraulic fracturing to extract natural gas from rock is one of the most dangerous threats to workers at wells blossoming across the U.S., a government safety researcher said.
About four out of five air samples from well sites in five states in the past two years exceeded recommended limits for silica particles, said Eric Esswein, an industrial hygienist at the National Institute for Occupational Safety and Health. The particles in sand dust created during the so-called fracking process can lodge in the lungs and cause potentially fatal silicosis, he said today at a conference sponsored by the Institute of Medicine.
http://www.businessweek.com/news/2012-04-30/fracking-sand-threatens-gas-well-workers-researcher-says