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The union said it approved many parts of the ruling, especially the reduction in the coal dust standard from 2 milligrams per cubic metre of air to 1.5mg/cu.m.
The standards will reduce the amount of coal dust miners can be exposed to over a two-year period.
However, the union did express concern that the dust monitors would only be issues in coal producing areas of the mine.
Union officials said the balance of the rule should lead to a reduction in black lung disease.
The ruling didn’t prove as popular with other groups, with the National Mining Association challenging the rule in the Supreme Court.
It argues that the cost of implementing the ruling outweighs the health benefits and will further impact the weakening US coal market.
