Homeowners returning to their burned-out homes in southern California are facing the painful consequences of the US construction industry’s reliance on cheap plastics and petroleum-based building materials: Not only are these materials easily combusted in a wildfire, but they leave behind a toxic soup that has polluted waterways and poisoned air quality.

Hemp-lime builders in Oregon are working on one of the largest commercial projects in the United States for which their hemp-based building materials passed 1-hour fire-resistance testing.