There’s some potentially major news today that’s come out after a private meeting last night between families of some of the Upper Big Branch miners and the U.S. Mine Safety and Health Administration.

During the meeting, MSHA officials revealed something that I hadn’t heard about before:  In late 2009, agency officials approved a reduction in the amount of air flow Massey was required to provide to ventilate the working face of the mine’s longwall mining section.

The change was made when Massey’s Performance Coal Co. brought the longwall machien back to Upper Big Branch (it had been moved to another mine a few years earlier) in August 2009.

When Upper Big Branch used the longwall previously, MSHA required the company to be sure to have air volume of 60,000 cubic feet per minute flowing toward the longwall face. Under the new plan, approved in August 2009, Massey proposed — and MSHA approved — required air flow of 40,000 cubic feet per minute.

Now, one thing to keep in mind is that air volume required under that new plan was still more than the minimum of 30,000 cubic feet per minute required by MSHA regulations. And, the last information available about airflow on the longwall section prior to the explosion — from a fireboss report called out of the mine about 20 minutes before the blast — was a measurement of 56,000 cubic feet per minute. Also remember, though, that a big part of this investigation is trying to figure out why the measured airflow in the longwall area had been cut in half, from 100,000 cubic feet per minute to 50,000 cubic feet per minute, in the months prior to the explosion.

But I’m told that the families at last night’s MSHA meeting understandably wanted answers for why the agency approved a reduction in the ventilation required for the longwall at UBB. Kevin Stricklin, MSHA’s coal administrator, told me a little while ago that the agency is looking into the issue:

That’s something that the internal review is looking at to find out why. I understand why people are concerned about that, and we want to get to the bottom of that.