The plan was to make Japan self-sufficient in wood products.
Cedar forests now cover 18% of Japan. That's more than Japan's total farm land (11%).
The plan backfired. Over supply and cheap imports drove down the price of cedar. The environment suffered — the soil eroded and the water table dropped. In the 1970s, it became clear that allergies to cedar pollen were skyrocketing.
By 2008, 26.5% of the population had an allergy to cedar pollen (33.8 million people).
Foreign residents of Japan who've been in the country 2 years or more are also at risk of developing cedar allergies.
Japanese people spend trillions of yen a year on medications and treatments for cedar allergies (far exceeding the revenue of Japan's forestry industry).
The government spends 7 trillion yen a year on programs to reduce pollen. The cost to the economy in lost productivity has never been calculated. The total cost of cedar allergies since 1970 could be as high as 100 trillion yen.
Excessive cedar pollen essentially makes 33.8 million people sick for several months every year. In Tokyo, the cedar season starts at the end of January (or start of February) and peaks in late March and early April.
In cedar allergy season, you'll notice masks everywhere in Japan. It almost looks like a disease outbreak disaster movie.