A woman in her 40s who moved to Fukuoka following the 2011 nuclear disaster because she was concerned about radiation levels now has another thing to worry about for her young daughter's health: air pollution drifting over from China.
The woman, whose daughter attends kindergarten, said she checks online ministry and university forecast data on air quality almost every day.
The woman moved in Fukuoka from the Kanto region after the disaster at the Fukushima No. 1 nuclear plant. Now, she makes sure that her daughter wears a surgical mask when air pollution levels are expected to go up. She does not hang her laundry outdoors on such days.
Officials and health experts say the woman has cause for concern, as the air pollution blanketing many Chinese cities last month drifts over the East China Sea to Japan.
Masayuki Shima, professor of public health at Hyogo College of Medicine, advised people with asthma or other ailments not to go outdoors when levels of PM 2.5, particulate matter with a diameter of 2.5 micrometers or less, are high in the air.
“It is difficult to completely shut out air pollutants,” Shima said. “But people can take precautionary measures by staying indoors, instead of going out, and wearing a surgical mask when they go out.”
The air pollutants migrating from China are PM 2.5, which are less than one-30th the thickness of a hair.
These fine particles, also found in car exhaust and industrial wastes released from factories, can reach deep into the lungs and blood vessels and cause asthma, heart disease and lung cancer.
According to a survey of 19 hospitalized patients aged 8-15 with severe asthma over an extended period, the chances of experiencing symptoms rose by nearly 10 percent when the daily average of PM 2.5 is above 24 micrograms per cubic meter.
The survey monitored their conditions for five months.
The Sukoyaka Kodomo welfare club, a social welfare corporation based in Toyama, Toyama Prefecture, does not allow pupils at two nursery schools it runs in the city to play outdoors when air pollution levels are high, and the windows of the schools are also kept shut. The corporation introduced the rule in mid-January.
As the smog and air pollution produced in China is blown eastward by winds over Japan, the impact is being felt in many parts of the nation, particularly in the west.
Many alarmed citizens started accessing the Japanese Environment Ministry's online data when the news media reported on the air pollution and smog smothering many Chinese cities since last month.
The ministry releases data from its Atmospheric Environmental Regional Observation System, which monitors air pollution, and Sprintars (Spectral Radiation-Transport Model for Aerosol Species), a Kyushu University effort that forecasts the spread of air pollutants and yellow sand, which is carried by winds from China's dry desert regions.
The Japanese government set regulations in September 2009 that established the legal limit of the concentration of PM 2.5 at an average of 35 micrograms per cubic meter a day or less, and an average of 15 micrograms per cubic meter a year or less.
According to a survey released in fiscal 2010, the first after the regulations were set, the annual average exceeded the legal cap at 34 of the 46 monitoring spots across the nation.
Most of the 34 sites were located in western Japan. However, pollutants drifting from China can reach farther east.
The cities of Kawasaki and Chiba in the Kanto region were among the sites where air pollution levels were above the safety standards.
The pollutants have also been detected in rime on trees in Zao, Yamagata Prefecture, since the mid-1990s.
Fumitaka Yanagisawa, professor of environmental chemistry at Yamagata University who has researched the spread of pollution, said suspended pollutants from China fall in various forms.
“They fall as part of acid snow in winter,” he said. “In spring, they fall, contained in photochemical smog and acid rain, after they are attached to yellow sand.”
On Jan. 31, average readings in Fukuoka of PM 2.5 at its six monitoring sites exceeded the legal daily limit. However, the ministry said the high figures do not mean that residents are immediately at great risk.
Ministry officials also said there was not a spell of several days in a row this year when readings were significantly higher than the safety standards.
But Toshihiko Takemura, associate professor of meteorology at Kyushu University’s Research Institute for Applied Mechanics, which helped develop the Sprintars air pollution forecasting model, sounded an alarm, referring to people with existing conditions.
“Polluted air may not pose a threat to many healthy people,” said Takemura, who researches transboundary air pollution from China. “But it could trigger a serious condition for people who are already suffering from an illness.”
(This article was written by Ryosuke Yamamoto and Seinosuke Iwasaki.)
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