Washington — The Mine Safety and Health Administration has extended until Sept. 11 the comment period for a proposed rule on worker exposure to respirable crystalline silica.
On July 13, MSHA published a proposed rule that would lower the permissible exposure limit for silica to 50 micrograms per cubic meter of air over an 8-hour time-weighted average. The proposed PEL is half the previous limit and identical to the PEL OSHA established in 2016.
Workers can inhale silica dust during operations including mining, cutting, sawing, drilling, or crushing materials such as rock and stone. Crystalline silica can damage lung tissue and lead to black lung disease, chronic obstructive pulmonary disease or incurable silicosis.
OSHA estimates that 2.3 million workers are exposed to silica dust annually.
