Chinese pollution reaching Japanese cities, says Tokyo
Tokyo (AsiaNews/Agencies) – Japan accuses China of polluting its cities. Vast clouds of photochemical smog smothered more than 20 prefectures in Japan on May 9 as a result of ozone carried by westerly winds from China.
Researchers at Kyushu University and the National Institute for Environmental Studies produced a report based on their simulations of ozone concentration at ground level. Thick plumes of high-density ozone (O3) hit wide areas from northern Kyushu to the Kanto region, they said.
Tokyo is concerned that Chinese pollution is crossing the sea and wants international rules to regulate cross-border pollution.
In the 1970s, parts of Japan were often clouded by pollution created when sunlight acts on exhaust gases from motor vehicles and factories, which include nitrogen oxides and other pollutants, generating ozone and other oxidants.
The phenomenon was less common in later years as a result of counter measures but has recently started to occur with more frequency in northern Kyushu and over the Sea of Japan near Honshu.
Japanese experts lay the blame on China. A group of researchers conducted simulation studies with Kyushu University researchers led by Itsushi Uno, a professor of ocean-atmosphere dynamics at its Research Institute for Applied Mechanics.
They first calculated pollutant emissions in Asia using energy consumption data and statistics about the number of road vehicles.
The simulations showed that at 3 pm on May 6, high-density ozone areas appeared along China's coastal regions, while levels were low in Japan.
But as westerly winds blew along the northern periphery of a high-pressure system in the East China Sea, high-density ozone areas spread from China to Japan from May 7 to 9.
On May 9, a high-pressure system blanketed the Japanese archipelago, bringing in hot, sunny weather. And as the mercury soared to this year's highest levels, photochemical smog was seen in many areas. In Niigata, a smog warning was issued for the first time since observation started in 1972.
Toshimasa Ohara, chief of the national institute's Regional Atmospheric Modeling Section, says that Japan must introduce countermeasures.
“We should be reducing emissions from Japan that cause photochemical smog, but at the same time it is necessary to create international rules to regulate cross-border pollution,” he said.
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