The time bomb is in place. Kyodo News reveals that Millions of homes have asbestos roofing in Japan.

Quote Originally Posted by Japan Times
OSAKA (Kyodo) Roofing tiles used in up to 5 million homes in Japan -- 20 percent of the total -- are believed to contain asbestos, tile makers said Saturday.

The tiles include those made by Kubota Corp. between 1961 and 2001 and by the Matsushita Electric Works group between 1971 and 2003.
...
A Kubota Matsushitadenko official said there is little possibility the tiles scatter asbestos "if used in a normal manner."

But experts point out that compared with demolition work for schools and other public facilities, measures to prevent asbestos from getting into the air when homes are torn down are insufficient.
This comes only days after the scandal of asbestos in Japanese train stations broke.

Of course, "used in a normal manner" does not take natural disasters into account. When we see the number of tiles falling off roofs after typhoons or earthquakes in Japan, there must be a serious risk of asbestos infection several times a year in most of Japan.