Nearly two months after an explosion at Massey’s Upper Big Branch mine killed 29 workers, investigators finally entered the mine on Wednesday in search of the
“„The mine rescue teams advanced for about an hour 1,000 feet into the mine, before high levels of carbon monoxide and methane forced them to retreat, said Amy Louviere, a spokeswoman for the federal Mine Safety and Health Administration. She said the teams took air readings with hand-held monitors, along with bottle samples to be evaluated Wednesday.