TOKYO -- China appears to be making progress in its battle against air pollution, but its commitment to protecting the environment still faces its biggest test.
In recent months, air pollution levels in major cities nationwide have dropped significantly. There have been few news reports about cities being blanketed by thick smog containing harmful PM2.5 particulates so far this year.
The fine particles, which measure less than 2.5 micrometers in diameter and are believed to pose serious health risks, have in the past caused serious concerns in Japan when high concentrations spread from China to Kyushu and other parts of the country.
But high levels of PM2.5 from China have not been a problem for Japan this year. One reason appears to be linked to weather patterns, but some experts also point to a vast improvement in the air quality in many Chinese cities.
Whether that remains the case, however, may depend on how serious the administration of President Xi Jinping is about sticking to its ambitious policy goals.
In 2013, China started measuring PM2.5 levels in the air on an hourly basis. Currently, such measurements are being made at about 160 locations. But not enough data has been collected yet to be of much use.
Average concentrations of PM2.5 have been trending lower in Beijing, where measurements started in 1996, says He Kebin, a professor at Tsinghua University's Division of Air Pollution Control.
One of the causes of PM2.5 is sulfur dioxide emissions. SO2 emissions are said to have decreased markedly since peaking in 2006. Behind the fall is the introduction of punitive measures against regions that have failed to achieve their reduction targets.
The amount of nitrogen oxides spewed into the atmosphere in China is also likely to fall in the coming years. That is because the government's 12th five-year economic plan sets targets for cutting NOx emissions.
Annual average PM2.5 concentrations in such cities as Beijing and Tianjin are around 100 micrograms per cubic meter, far above the 15-microgram limit under Japan's environmental standards.
In 2013, the government set a target of lowering the average PM2.5 concentration in Beijing to 60 micrograms in 2017 and 50 micrograms in 2020. The plan targets a nationwide average of 35 micrograms by 2030.
"The PM2.5 scare in 2013 came as an eye-opener for the Chinese, making them keenly aware of the urgent need to do something about the environmental problems," said Kenji Someno, a research fellow at the Tokyo Foundation -- a private think tank -- and an expert on environmental problems in China.
Averting a backlash
Many Chinese became aware of the health threat posed by PM2.5 after experiencing firsthand just how bad it was. Concerns that air pollution could trigger a massive public backlash against the government prompted Chinese leaders to develop the action plan.
The Xi administration's decision to prioritize cleaning up the environment is also reflected in its policies on global warming. Last year, Xi pledged to ensure that the country's CO2 emissions will start declining after peaking around 2030. The Tokyo Foundation's Someno says they may peak much earlier.
In addition to showcasing to a domestic audience his resolve to bring about a cleaner China, Xi's promise also appears aimed at taking the leadership in the international negotiations for a new climate change treaty slated to be concluded by the end of this year.
Observers say China wants its policy efforts on PM2.5 and global warming to help transform the country's industrial structure in a way that increases the international competitiveness of its industries.