This is not evidence that unions make labour more dangerous.
The last paragraph even in your link is this;
"Tougher enforcement of laws, with higher penalties, and stronger safety standards are essential. But unionized miners have the power to enforce those standards before there's an accident, and they can prevent the speed-ups, overwork, and shortcuts that are common in non-union mines, like Upper Big Branch, and that contribute to the dangers of the job.
If Congress and Obama want to do something to save miners' lives, they should first of all protect and strengthen their right to organize."
The last paragraph even in your link is this;
"Tougher enforcement of laws, with higher penalties, and stronger safety standards are essential. But unionized miners have the power to enforce those standards before there's an accident, and they can prevent the speed-ups, overwork, and shortcuts that are common in non-union mines, like Upper Big Branch, and that contribute to the dangers of the job.
If Congress and Obama want to do something to save miners' lives, they should first of all protect and strengthen their right to organize."