<p>A mysterious pestilence has befallen Japan’s primeval forests, leaving behind the remains of dead trees. Osamu Nagafuchi, an environmental engineer with a passion for the island and its rugged terrain, believes he knows the culprit: airborne pollutants from smog-belching China, hundreds of miles away.<br /><br /></p>.<p>For years, Nagafuchi’s theory was ignored by fellow scientists and even mocked by bureaucrats in the Japanese national government. But Japan has begun taking his warnings more seriously, as the nation has been gripped by a health scare over rising levels of potentially dangerous airborne particles that have swept into other parts of Japan and that many now believe were produced by China. These fears have reached a new level recently as China itself has issued more public warnings about the growing health risks from its cities’ gray, soupy air. <br /><br />Whatever the cause, the tree die-off is a worrisome turn for this small, mountainous island off Kyushu, whose moss-carpeted forests provide a rare patch of primitive nature in an otherwise densely populated nation. There are fears here that a growing smog problem could scare off the hikers and other ecotourists upon whom many of the island’s 14,000 residents depend for their livelihoods. Most visitors come to see Yakushima’s majestic cedar trees, which have so far been unaffected by the mysterious ailment killing the pines. The cedars won the island the distinction of a UNESCO World Heritage site in 1993. The biggest remaining tree, the gnarled Jomon cedar, measures 16 feet around at the base and is estimated to be at least 2,600 years old. <br /><br />Nagafuchi, a professor of ecosystem studies at the University of Shiga prefecture in central Japan, said he noticed the problem when satellite photographs showed a large increase in the number of dead trees between 1992 and 1996. <br /><br />Nagafuchi, then a public employee for a city in Kyushu, had already found blackened snow while hiking to Yakushima’s mountain tops in 1992. <br /><br />He started analysing the snow as a sort of hobby and found that it contained silicon, aluminium and other byproducts from the burning of coal. He theorised that the pollutants were carried here from China. The discovery drove Nagafuchi to become a university professor, and research on Yakushima. <br /><br />He has set up small monitoring stations around the island to measure levels in the air of ozone and sulphur emissions, byproducts of burned coal or automobile exhaust. Recently, Nagafuchi climbed to the highest of those stations, atop Mount Kuromi, a peak 6,000 feet above the sea. With downloaded data from the station’s digital recorder, he pointed out the thin, gauzy haze that clouded the peak. <br /><br />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 PM 2.5, small enough to become embedded in human lungs. <br /></p>
<p>A mysterious pestilence has befallen Japan’s primeval forests, leaving behind the remains of dead trees. Osamu Nagafuchi, an environmental engineer with a passion for the island and its rugged terrain, believes he knows the culprit: airborne pollutants from smog-belching China, hundreds of miles away.<br /><br /></p>.<p>For years, Nagafuchi’s theory was ignored by fellow scientists and even mocked by bureaucrats in the Japanese national government. But Japan has begun taking his warnings more seriously, as the nation has been gripped by a health scare over rising levels of potentially dangerous airborne particles that have swept into other parts of Japan and that many now believe were produced by China. These fears have reached a new level recently as China itself has issued more public warnings about the growing health risks from its cities’ gray, soupy air. <br /><br />Whatever the cause, the tree die-off is a worrisome turn for this small, mountainous island off Kyushu, whose moss-carpeted forests provide a rare patch of primitive nature in an otherwise densely populated nation. There are fears here that a growing smog problem could scare off the hikers and other ecotourists upon whom many of the island’s 14,000 residents depend for their livelihoods. Most visitors come to see Yakushima’s majestic cedar trees, which have so far been unaffected by the mysterious ailment killing the pines. The cedars won the island the distinction of a UNESCO World Heritage site in 1993. The biggest remaining tree, the gnarled Jomon cedar, measures 16 feet around at the base and is estimated to be at least 2,600 years old. <br /><br />Nagafuchi, a professor of ecosystem studies at the University of Shiga prefecture in central Japan, said he noticed the problem when satellite photographs showed a large increase in the number of dead trees between 1992 and 1996. <br /><br />Nagafuchi, then a public employee for a city in Kyushu, had already found blackened snow while hiking to Yakushima’s mountain tops in 1992. <br /><br />He started analysing the snow as a sort of hobby and found that it contained silicon, aluminium and other byproducts from the burning of coal. He theorised that the pollutants were carried here from China. The discovery drove Nagafuchi to become a university professor, and research on Yakushima. <br /><br />He has set up small monitoring stations around the island to measure levels in the air of ozone and sulphur emissions, byproducts of burned coal or automobile exhaust. Recently, Nagafuchi climbed to the highest of those stations, atop Mount Kuromi, a peak 6,000 feet above the sea. With downloaded data from the station’s digital recorder, he pointed out the thin, gauzy haze that clouded the peak. <br /><br />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 PM 2.5, small enough to become embedded in human lungs. <br /></p>