Between 2003 and 2007, those mines receiving assistance from the office recorded a 66% drop in fatality incidence rate, or the number of fatalities per 200,000 hours worked.
Those mines staffed by five or fewer workers had a higher fatality rate over larger mines prior to 2003, it added.
The Small Mines Office has assisted more than 6500 US operations with customised safety and health programs since its establishment, and that aid has helped bring the rate from 0.053 between 2000 and 2002 to 0.018 between 2003 and 2007.
Meanwhile, those small mines that did not request assistance directly from the office also saw a reduction in their fatality rate, albeit much less significant – from 0.053 to 0.045 during the same time periods.
Those larger operations with more than five employees reduced fatality rates from 0.021 to 0.017 during the period.
“MSHA's Small Mines Office has clearly played a major role in assisting small mine operators in reducing the workplace hazards that can cause deadly mining accidents," said MSHA acting assistant secretary of labor for mine safety and health Richard Stickler.
“These efforts have demonstrated that good health and safety practices need not be expensive, time consuming or complicated."
According to agency statistics, mines with five or fewer employees make up about 50% of mining operations in the US.