The discovery drove Nagafuchi to quit his city job and eventually become a university professor, doing much of his research on Yakushima. He has set up small monitoring stations around the island to measure levels in the air of ozone and sulfur emissions, which are typically the byproducts of burned coal or automobile exhaust.
On a recent afternoon, Nagafuchi climbed to the highest of those stations, atop Mount Kuromi, a windswept peak that rises 1,828m above the sea below. After hooking up his laptop to download data from the station’s small digital recorder, he pointed out the thin, gauzy haze that clouded what he said should have been pristine air.
“The worst is when winds blow from Beijing and Tianjin,” two Chinese cities about 1,450km to the northwest, said Nagafuchi, 62, who visits Yakushima once a month to collect the data readings. “This is proof that when such a big country industrializes, its effect will spread everywhere.”
When they first started publicizing the findings in the mid-1990s, Nagafuchi and his main partner, Kenshi Tetsuka, an islander who started a small environmental group to protect the pines, were at first derided by forestry officials and established scientists who said they were sensationalizing the die-off to get public attention. Some scientists questioned why the tree deaths slowed even as China’s pollution problems have grown. Nagafuchi says he believes the pollution quickly killed off the weak trees, leaving the hardier ones.
His ideas began to win limited acceptance in the early 2000s, amid evidence of a growing influx of Chinese pollutants across Japan. The national government’s Forestry Agency began to allow Nagafuchi to set up his monitoring stations, and is doing joint research with him and Tetsuka, though it still believes the deaths are caused by an infestation of bugs and a runaway population of deer, which can strip small trees of pine needles.
They point out that there had been die-offs of pine trees on Yakushima even before China’s economic takeoff.
“We don’t agree with him, but we respect his research,” said Hiroharu Ijima, a Forestry Agency official on Yakushima.
Public anxieties about environmental effects from China have soared this year, after Beijing recorded alarming increases in pollution levels. That was followed by officials in western Japan issuing warnings in their own cities of high levels of particulate matter measuring 2.5 micrometers or less, known as PM2.5, that are small enough to become embedded in human lungs. Several Japanese cities have issued warnings this year for residents to stay indoors when the pollutant levels spike.
When the air grew particularly hazy on Yakushima one day last month, local officials asked if they could use one of Nagafuchi’s monitoring stations to measure PM2.5. The level was above government-recommended safe levels, prompting officials to order a local elementary school to cancel a field trip to a nearby forest.