In a May 2 letter to U.S. Assistant Labor Secretary Joseph Main, the NMA outlined issues rendering compliance impractical within given timeframes. “The protection of our workforce demands effective solutions,” NMA CEO Hal Quinn said. “We are left with no choice but to seek intervention.”

Under the rule, beginning August 1, operators must take “immediate corrective actions” for dust sampling, said the NMA, but with real-time measurement technology unavailable until at least Q1 2015.

The full shift dust sampling requirement, moreover, stipulates a method “not sufficiently studied” by the unrealistic deadline, the NMA said. Accordingly, without time to complete thorough analysis and planning on mine schedule integration, “operators can only guess” at when sampling is necessary.