Federal officials say almost every mine sample taken since August would meet tougher limits on coal dust.
A U.S. Mine Safety and Health Administration news release this week said 99 percent of about 7,500 samples were below the new standard.
Initial requirements of the coal dust rule became effective Aug. 1. The fed- eral rule proposed in 2010 aims to reduce black lung disease.
In February 2016, better monitoring equipment will be required. In August 2016, the allowable concentration of coal dust will drop. Officials will be able to cite violations based on single samples, instead of average levels.
Federal officials said mines met the new standard despite voicing concerns they couldn’t.