WASHINGTON (AP) — Coal miners will be better protected from poisonous silica dust that has contributed to the premature deaths of thousands of mine workers from a respiratory ailment commonly known as black lung disease, the Labor Department said Tuesday as it issued a new federal rule on miners’ safety.

The final rule, announced by Acting Labor Secretary Julie Su, cuts by half the permissible exposure limit for crystalline silica for an eight-hour shift.

Mine workers, community advocates and elected officials from Appalachian states have pushed for the stricter rule, noting that health problems have grown in recent years as miners dig through more layers of rock to gain access to coal seams when deposits closer to the surface have long been tapped. The increased drilling generates deadly silica dust and has caused severe forms of pneumoconiosis, better known as black lung disease, even among younger miners, some in their 30s and 40s.