A federal appeals court has temporarily blocked enforcement of a new rule to limit silica dust exposure for coal and other miners.

The rule, from the Mine Safety and Health Administration (MSHA), was imposed last year in response to an epidemic of severe black lung disease among coal miners. Reporting by NPR, Public Health Watch, and Louisville Public Media documented more than 4,000 cases of advanced black lung that had been previously unreported.

The disease is incurable and fatal, and the severe form is connected to overexposure to toxic silica dust during coal mining, as well as rapid progression of disease and onset among younger miners.

The new rule cut in half the amount of silica dust permitted around coal and other miners during an eight-hour shift. The rule also imposed tougher enforcement measures and required regular testing of miners for lung disease.  

Government researchers first recommended stricter silica dust exposure limits and enforcement more than 50 years ago.

Enforcement of the new rule was to take effect April 14 for coal mines, and next year for others, including metal and stone mines and sand and gravel operations.

Last week, the National Sand, Stone and Gravel Association sought an emergency stay of the rule in the 8th U.S. Circuit Court of Appeals in St. Louis. Coal mines have long been inspected for excessive coal and silica dust, and coal miners were tested for black lung under a government program for decades. But metal and other mines did not have those requirements and would have to adapt to what the industry considered new and expensive dust and miner testing.

On Friday, the court granted a temporary administrative stay. The court will now consider whether to block enforcement permanently or allow  enforcement to begin.

The mining industry argued in court filings that enforcing the rule will cause “irreparable harm” to mining companies. But Chris Williamson, the former assistant secretary of labor in charge of MSHA during the Biden administration, said Monday that the health and safety of miners is at risk. Williamson developed and pushed hard for the new rule.

“I respect the judicial review process,” Williamson told Public Health Watch. “But I’m concerned that if the court steps in at the last hour to block enforcement, the miners who waited almost 50 years for these protections are going to be irreparably harmed.”