This paper focuses on the long-term trend and current status of air pollution in China. In particular, fine particulate matter (PM
2.5) in Beijing city was introduced. The annual number of scientific journal publications regarding PM
2.5 in China has been increased from zero before 2000 to more than 100 in the past two years. The concentrations of PM
10 in Beijing have been decreased from 169±94 µg/m
3 in 2001 to 109±73 µg/m
3 in 2012. Researchers should note that Beijing is not a representative city of China because it was uniquely developed due to the hosting of the 2008 Summer Olympic Games. The concentrations of PM
2.5 in Beijing have almost been constant at a level of 100 µg/m
3 from April 2010 to October 2013 except in January 2013, showing remarkably high monthly average PM
2.5 concentrations (200 µg/m
3). This highly polluted situation was probably due to a tentative meteorological condition in that period, and this did not cause any elevation of PM
2.5 concentration in Japan. The chemical composition of PM
2.5 in 2010 was similar to that in 2000, however, the content of carbonaceous species in PM
2.5 was likely to have decreased from 2000 to 2010 when compared to water-soluble ionic species. The concentrations of air pollutants decreased by up to 50% in the summer of 2008 due to Olympic Game related environmental control measures, but they increased again in 2009. It seems difficult for many Chinese cities to satisfy the ambient air quality standard for PM
2.5 even though the standard is not strict when compared to other countries. Since the status of atmospheric environment in China changes abruptly, the continuous monitoring is mandatory.
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