Which materials or environments are most at risk of containing anthrax?

The biggest risk materials are horsehair plaster and old animal hair insulation. Both were common in buildings before synthetic alternatives were widely available. Work environments tied to hides, wool, bone, and tanning are also historically connected to anthrax exposure. Damp or damaged areas where spores could be released are of particular concern, especially during renovation or demolition work. It’s worth noting that intact materials generally pose little risk — the danger comes when they’re disturbed.