OSAKA, Feb. 21 (Xinhua) -- A Japanese professor of environmental solutions technology in the prefecture of Shiga has called on China to impose tighter regulations on flue gas and vehicle exhaust emissions and to use weather forecasting system to avoid immediate health risks.
In a recent interview with Xinhua, Professor Yoichi Ichikawa of Ryukoku University said that the most effective long-term measure to raise air quality in Chinese cities would be to implement thorough controls on the total amount of pollutants containing sulfur dioxide and nitrogen oxide emitted from factories and vehicles.
He said these controls should be based on geographic and meteorological considerations, a suggestion that entire regions, rather than single locales, should work together to resolve the issue.
Analyzing the dense smog observed in some Chinese cities since January, Ichikawa attributed the frequent occurrence of such environmental situations to the emergence of "temperature inversion layers" caused by prominent radiation-cooling this winter.
Figures released on Sunday by China's Ministry of Environmental Protection showed that 42.7 percent of 74 Chinese cities reported higher-than-normal PM2.5 reading. PM2.5 refers to fine particulate matter that is 2.5 microns or less in diameter, and the highest average reading in a single day was 426 micrograms per cubic meter, or 5.7 times the country's standard of 75 micrograms.
PM2.5 readings were also excessive in all 74 cities for about half of the holiday period, which lasted from Feb. 9 to 15, the ministry said.
Northern China's Tianjin municipality, for example, saw PM2.5 level hit 577 micrograms per cubic meter from 10 a.m. local time on Feb. 9 to 2 a.m. on the following day, and the readings were the highest among all 74 cities, said the reports.
Ichikawa said that even when the overall level of air-polluting emissions from industry, automobiles and homes do not change much, the occurrence of this phenomenon actually depends considerably on meteorological factors.
"Compared with other years, many places in China have been challenged by colder weather this winter, so it has often led to radiation cooling in the atmosphere by which colder and heavier air containing various pollutants are likely to remain in place, especially at night.
"In other words, smog can occur anytime the primary mechanisms of air pollution formation are active," Ichikawa said.
Given another example similar to this winter's Chinese situation, the professor cited the well-known "London Fog" in 1952, which killed about 8,000 people. It was the worst case of smog occurrence recorded in history.
Ichikawa mentioned lessons Japan learned when the country had to give the most serious attention to tackling pollution problems in the late 1960s and 1970s in major cities and industrial zones.
The professor said the air pollution worsened first with soot from factories, then sulfur dioxide, followed a little later by more air pollution due to automobile exhaust.
"During the worst period, we had to hold dedicated Diet sessions or 'Pollution Diets' that discussed nothing but environmental pollution to quickly control the situation," Ichikawa said.
Japan was then urged to prevent the spread of air pollution caused by cars. The professor, however, noted that the pollution levels, which worsened due to automobile exhaust, did not meet the national standards quickly in comparison with improvements in flue gas. This was due to Japan's fast-growing fleet of automobiles, which government measures could not catch up with.
"Although we imposed regulations on emissions from motor vehicles which led to government-mandated emission control systems installed in every car, the total amount of air pollutants has not decreased as much as we expected," Professor Ichikawa added.
Ichikawa said that in order to protect local residents in China from the pollution, major factories and buildings, in particular those using coal, should be urged to invest in pollution control equipment while the government imposes regulations on total allowable volumes of pollutants within a region or wider areas.
He said such measures should be discussed since this issue concerning the atmosphere can never be resolved by a single city or district.
At the same time, the professor pointed out that establishing an "air pollution forecast system" using computer simulations could be a good option to avoid health risks for the time being.
He said that information and computer technologies have advanced considerably and specialists are now able to establish an advisory or warning system which can issue orders for temporary suspension of factory operations or flexible shifting of production to other days, for example, to adjust the pollution levels.
In Beijing, concerned agencies are already evaluating all possible solutions to the severe pollution that hit not just Beijing but other major industrial cities in the county.
Surrealistic impression shown in fog
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