Japan faces a national health crisis as pollen allergies from decades-old monoculture forests affect millions. The crisis stems from post-WWII reforestation efforts that prioritized rapid regrowth using only Japanese cedar and cypress trees. These species now blanket vast areas, releasing enormous pollen clouds that cause seasonal hay fever with severe health impacts across the country.

The economic toll reaches $1.6 billion daily during peak allergy seasons, prompting Japan to declare allergies a national social problem. Government officials aim to reduce pollen by 50% within 30 years by cutting sugi tree coverage by 20%. This massive undertaking requires careful forest management to prevent soil erosion while meeting climate targets.

Cities like Kobe lead biodiversity restoration projects, converting plantation forests into mixed woodlands. These initiatives demonstrate how selective clearing and natural regrowth can restore ecosystems while reducing pollen. Monitoring shows wildlife returning to restored areas, with cut trees repurposed for heating and construction, creating potential economic benefits alongside health improvements.