People living in the Greeley neighborhood near Montana Resources’ open-pit Continental mine are concerned about what’s in the dust blowing in from the mine that occasionally coats their homes and vehicles. In a city where past mining left a legacy of soil and water pollution, is the air unsafe, too? Montana Resources and the DEQ say yes, but a new study points out shortcomings in their data, and the EPA is reconsidering its standards for safe particulate matter.