The Environmental Protection Agency is investigating the discovery of asbestos fibers, similar to those found in Libby, at an air monitoring station in Helena last October.

An official with the EPA said on Wednesday that he was surprised at the one-time detection, in part because the monitoring site was set up as part of a risk assessment in Libby.

"We tried to pick Helena and Eureka as two places that would be representative of this area, but outside of our area of concern," said Mike Cirian, the EPA's remedial project manager in Libby. "Then, during the first round of sampling, we got a hit in Helena."

Eleven subsequent samples didn't contain any asbestos, and Cirian said the amount detected probably doesn't pose a health hazard. Still, the asbestos wasn't supposed to be there in the first place, and Cirian said the EPA needs to figure out its source.

Asbestos typically falls out of the air fairly quickly, so Cirian said he doesn't think this blew into Helena from Libby.

John Podolinsky with the state's DEQ Asbestos Control Program theorized that the material could have originated from someone remodeling an attic near the air monitoring site in the 1700 block of Missoula Avenue.

Cirian adds that it could have blown in from a rail line, or it could be caused by some industrial plant.

"We are doing some research there on what kind of corridors are possible," Cirian said.

The air monitoring takes place every five days, and is expected to continue for the next year.

Asbestos burrows into lungs and can cause severe and deadly respiratory problems including lung cancer, asbestosis or mesothelioma, a cancer triggered only by asbestos. Asbestos was contained in vermiculate processed in a Libby plant, which became a popular attic insulation, cement additive and soil conditioner used worldwide.

Asbestos from different locations carries certain distinct fingerprints, and the Helena sample included six Libby "amphibole" detections. The six amphibole are the highest asbestos background concentrations measured to date for a site not expected to be contaminated.

However, to put that in context, Podolinsky said federal standards are 70 amphiboles per milliliter of air.

"So six fibers should tweak people's interest, but it's under the air levels," he said. "Still, there shouldn't be any."

Ted Linnert, the community involvement coordinator in Libby, also wasn't alarmed by the finding, although he was surprised.

"The ironic thing is we chose Helena and Eureka to get a background, then we get detects in one of what we thought would be a background location," Linnert said.

Reporter Eve Byron can be reached at 447-4076 or on-line at eve.byron@helenair.com