"Minnesota's Vapor Trail: Tracking Toxic Gases in Basements"

"Discovery that contamination in soil can vaporize and seep into homes has prompted a statewide review of polluted sites."

"The discovery that toxic vapor can rise from contaminated groundwater has undercut decades of pollution cleanup efforts in Minnesota, prompting state regulators to revisit 293 cleanup sites to determine if contaminants that once seemed contained underground are producing health hazards today.

While cleanups in southeast Minneapolis and St. Louis Park have been well publicized, the Minnesota Pollution Control Agency has quietly undertaken a much broader review, and found another 53 pollution sites, from Bagley to Rochester, where vapor intrusion is being addressed. The review is ongoing at 80 additional sites.

State pollution officials also must decide whether to revisit 268 Superfund sites that were closed out years ago, because old cleanup strategies didn’t account for vapor risks."

Jeremy Olson reports for the Minneapolis Star Tribune March 30, 2014.