Abstract:

In August and September of 2008 Beijing held the 29th Olympics and 13th Paralympics successfully. The atmospheric particulate matter was collected during this period on the campus of China University of Mining & Technology (Beijing) which is about 3 kilometers from central Olympic Stadium. The mass concentrations and morphological types of the airborne particles were investigated. The results showed that the mass concentrations of PM₁₀ and PM_2.5 during the Olympics were well below the national standard II (150 μg/m³) and USA-EPA daily mean standard (65 μg/m³)， respectively, with the 12-hour means ranging between 7.64 μg/m3 and 81.63 μg/m3 for PM₁₀ and between 1.91 μg/m³ and 54.59 μg/m³ for PM_2.5. The 12-hour concentrations of PM10 during Paralympics ranged between 33.83 μg/m³ and 106.36 μg/m³, which are higher than those during the Olympics but are still lower than the national standard II. Mass concentrations of PM_2.5 during the Paralympics samples ranged between 15.29 μg/m³ and 88.30 μg/m³, and the PM_2.5  levels during most days of Paralympics were relatively low, except 6th, 7th and 14th of September when the PM_2.5  level exceeded USA-EPA daily mean standard. The PM_2.5 /PM₁₀ ratios during the Olympics and Paralympics were in the range between 0.26 and 0.86, mostly higher than 0.5, demonstrating a predominance of the PM_2.5  in PM10. Compared with previous years, mass concentration of PM_2.5  and PM₁₀ are both in a decreasing trend. The microscopic morphologies and size distribution of particle samples were further examined by FESEM and Image Analysis. Spherical particulate, soot, irregular minerals and unknown fine particles were identified. The number-size distribution of these samples showed that the particles are mainly concentrated in the size range of  0.1-0.2 μm, in which the spherical particles are dominated. All data indicated that the pollution of the airborne particles in Beijing city during the Paralympics is more severe than that during the Olympics.

Key words: Olympics, Paralympics, atmospheric particles, microscopic morphology, Beijing