Chinese pollution reaching Japan

TOKYO: 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 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 calculated emissions in Asia using energy data and statistics about the number of road vehicles.