SANTA ROSA (KPIX 5) – As the effort to rebuild from the wildfires in wine country begins, authorities have issued a warning about toxic materials in ash and debris.

“I want to want to warn people there are risks once we allow people to areas where houses have burned to the ground,” Mayor Chris Coursey said Wednesday. “These are risks to your health and financial risks.”

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Sonoma County says it is working on a re-entry plan for affected homeowners to visit what is left of their properties. No cleanup work will start until sites have been declared safe and secure.

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“There can be chemicals and asbestos and lead, plus plastic particles. All of that within that debris,” Christine Sosko, Sonoma County’s director of environmental health, told KPIX 5. “So, we are very concerned about people rummaging through that, disturbing it, getting it to be airborne and inhaling it.”

The U.S. Environmental Protection Agency will be managing the removal of toxic materials from thousands of fire-scorched properties. Materials such as batteries, paint, solvents, flammable liquids, electronic waste and any materials that contain asbestos.

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“It varies from structure to structure, and home to home, based on what people had stored. If they have pools, they could have chlorine, they could have had a lot of things that have been compromised due to the fire,” said Brett Gouvea of Cal Fire.

“There’s a mixing of things that could have occurred. And it creates a hazardous materials environment to go in there and start sifting through things because they are no longer recognizable,” Gouvea went on to say.

Sifting or shoveling settled ashes makes them airborne again, possibly exposing people to dangerous materials, including carcinogens.

Homeowners are also being warned that unauthorized removal of debris and ash may jeopardize their ability to obtain financial assistance.

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As for a timetable on when people can return to the burned areas, there will be a town hall meeting this week to inform residents about the cleanup efforts.