Japan is gripped by mass allergies. A 1950s project is to blame | Hacker News

Japan’s widespread pollen allergies are linked to postwar cedar planting policies.

A BBC discussion says mass cedar plantations helped create today’s cedar pollen problem.

Many plantation forests are now overgrown or unmanaged as forestry workers age or disappear.

That makes it harder for Japan to address both forest health and a long-running public health issue.