Aerosol Chemical Compositions of Beijing PM₁ and Its Control Countermeasures

The mass concentrations of sulfate, nitrate, ammonium products, organic matter and black carbon are measured at urban Beijing during summer, autumn of 2007 and winter, spring of 2008. Combining assessment of major chemical compositions in less than 10 micron particles with at least an entire year data from various rural and urban sites in 16 areas of the world, the concentration level of mineral aerosol in China, which is partially a result of sand and dust transported from desert areas and contributions from urban fugitive dust/fly ash sources, is found to be almost equivalent to or even higher than the sum of all kind of aerosols in urban Europe and North America, suggesting the control countermeasures for aerosol particle in diameter between 2.5 and 10 micron in China should not be neglected, especially when the country pays much attention to control the fine PM_2.5 particles. In urban Beijing, the averaged concentrations of PM₁ are around 94, 74, 66 μg·m^-3 and 91 μg·m^-3 for spring, summer, autumn and winter, respectively, with the annual mean of 81 μg·m^-3. The relative contributions of organics, sulfate, nitrate and ammonium product are about 41%, 16%, 13% and 8%, respectively. The black carbon and chloride contribute Beijing PM₁ about 11% and 3%, respectively. The fine mineral aerosol contributes about 7%. The key of control PM_2.5 is to reduce the main emission species and their chemical transformation of PM₁ particles, and the more important is to control the organic matter at Beijing, although Beijing's pollution control has been very difficult since 26 million people living there. To be scientifically, even if China's control countermeasures can achieve one hundred percent, it is also hard to reach the air quality level of Europe and North America, because of the higher background mineral aerosol level. The cost-effective control measures and new PM_2.5 standard considering the health of Chinese need to be further investigated.