The death toll does not include workers in the oil and gas sector, a group that is regulated by a separate federal agency, the Occupational Safety and Health Administration.

Seventeen of the 28 deaths last year occurred in metal and non-metal mines. Eleven of them were accidents at coal mines, a sector that has seen employment decrease significantly in recent years, especially in Appalachia, as operators cut ties with costly underground operations to better compete with cheaper western coal and a plentiful supply of natural gas.

The “Massey Effect”

MSHA chief Joe Main attributed the decline in fatalities to the agency’s improved oversight tools, including better outreach and training with the industry, enhanced regulation of mines with chronic safety violations and the use of so-called special impact inspections that target “problem mines.”

Those special impact inspections kicked off in April 2010, shortly after the disaster at Massey Energy’s Upper Big Branch coal mine in West Virginia. Twenty-nine miners there were killed after an explosion — one of the worst mining disasters in U.S. history.

Massey’s former CEO Don Blankenship recently stood trial for his role in safety violations that regulators and many observers say led to the disaster. Last month, Blankenship was found guilty of conspiring to violate mine safety standards, but was acquitted on charges of securities fraud and making false statements to regulators. He faces up to one year in prison.