Mount Fuji was obscured behind a perpetual fog of exhaust and particulate matter. Traffic police were equipped with oxygen tanks on particularly hazardous days and many students were treated in schoolyards for inhaling photochemical smog.

This is what Tokyo was in the 1960s.

After World War II and especially during the decades of high-speed economic growth from the 1950s through 1970s, Japan's manufacturers were prodigious, largely unregulated polluters. Japan gained an unenviable reputation as the world's most toxic country. American biologist Paul Ehrlich described Japan as the developed world's "canary in the coal mine", a country so profoundly polluted that it became a test case for how high human tolerance levels could be.