[Status and distribution of atmospheric ultrafine particles during Olympics Games in Beijing].
OBJECTIVE
To understand the characteristics of size and concentration of the ultrafine particles (UFPs) during the 2008 Olympics in Beijing, as well as the influencing factors for number concentration of UFPs.


METHODS
Ultrafine particle monitor model 3031, manufactured by USA TSI Co., was used to monitor the daily number concentration of 20-500 nm particles, and descriptive analysis was conducted based on the data collected.


RESULTS
During the Olympics, the mean value of number concentration for 20-100 nm particulate matter is 5 920.43 particles/ cm3. Particles ranging 30-50 nm account for the largest portion(23.49%) among particles of all sizes. There are two peak values on the curve of 24 hours' number concentration for 20-100 nm particles, respectively, at noon and evening.


CONCLUSIONS
This paper indicates that the number concentration of ultrafine particles registered considerable reduction in the 2008's Olympics compared to the pre-Olympics years. And observation of the curves indicated that the number concentrations of the UFPs with bigger size are related to traffic volume, whereas for smaller size UFPs, illumination may be a more important influencing factor. Also there are significant correlations between number concentration and temperature as well as relative humidity.
Tong
Jian-yong
JY
Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing 100191, China.
Su
Chang
C
Guo
Yu-ming
YM
Wang
Jia-jia
JJ
Zhang
K Max
KM
Pan
Xiao-chuan
XC
D000393:Air Pollutants / Q000032:analysis*; D001272:Atmosphere; D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D007391:International Cooperation; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D013177:Sports
D000393:Air Pollutants; D052638:Particulate Matter