Early this afternoon, officials from the U.S. Department of Labor and its  Mine Safety and Health Administration will gather in Washington for a celebration to mark the 40th anniversary of the landmark federal Coal Mine Health and Safety Act of 1969.

Wait … The 40th anniversary? Wasn’t that last year? Well, yes. The law was signed on Dec. 30, 1969. But, MSHA’s celebration is officially to mark the effective date of the law, which for most provisions was March 30, 2010.

Wouldn’t today’s event be a great opportunity for the Obama administration to make some major announcement … Oh, like maybe that MSHA was going to get back on track with its initial promise to tighten the legal limit on coal dust that causes deadly black lung disease?

Folks often point to the Farmington Disaster as one of the defining events that pushed Congress to pass the 1969 Act. But my friend Paul Nyden here at the Gazette has chronicled the major role that disabled miners and the drive for justice for black lung victims played in passage of the law.

And in fact, the law set out a rigorous schedule for addressing black lung, aimed at eliminating the disease forever.

First, lawmakers set this initial limit:

Effective on the operative date of this title, each operator shall continuously maintain the average concentration of respirable dust in the mine atmosphere during each shift to which each miner in the active workings of such mine is exposed at or below 3.0 milligrams of respirable dust per cubic meter of air.

And then,within three years, the legal limit was to drop to 2.0 milligrams per cubic meter.

Finally, Congress demanded that regulators set a schedule for reducing the dust limits to a level:

… Which will prevent new incidences of respiratory disease and the future development of such disease in any person.

Now, we know that the current dust limit isn’t achieving this goal.  New cases of black lung continue to develop, and 10,000 miners have died from the disease in the last decade alone.

Since at least 1995, the National Institute for Occupational Safety and Health has recommended that MSHA tighten the dust limit to 1.0 milligrams per cubic meter. A Department of Labor advisory panel reached similar conclusions in 1996.

Last spring, it looked like Obama was going to do something about this. MSHA’s regulatory agenda published in May 2009 listed an item for lowering the legal dust limit.

But after Joe Main’s confirmation in October as assistant labor secretary in charge of MSHA, the new regulatory agenda that came out in December had been modified to include a proposal to reduce exposure to dust, but not actually tighten the legal limit. While MSHA hasn’t been speaking that clearly about all of this, their regulatory agenda language has been pretty clear: Lowering the exposure limit isn’t listed anymore.

Today’s celebration might provide a chance for Main or his boss, Labor Secretary Hilda Solis, to make clear their intention to tighten the dust limit — if, in fact, that’s what they intend to do.