Wow, Chromium-3 in Serpentine soils (common in Sierra Nevada and Coast Range foothills) is converted to Chromium-6 when cooked by #wildfire. The asbestos exposure risk alone is bad enough for wildland fire fighters working in dust stirred up by bulldozers.

Wildfires can turn harmless minerals in soils into contaminants, research shows
https://phys.org/news/2025-12-wildfires-harmless-minerals-soils-contaminants.html