title: [Concentrations of fine particulate matters and ultrafine particles and influenced factors during winter in an area of Beijing].
abstract: OBJECTIVE
  To study the concentrations of fine particulate matters and ultrafine particles and influenced factors during winter in an area of Beijing.
  
  
  METHODS
  Real-time monitoring of particles' mass and number concentrations were conducted in an area of Beijing from February 7(th) to 27(th), 2013. At the same time, the meteorological data were also collected from the Beijing meteorological website. Differences of the particles' mass and number concentrations during different periods were analyzed using Mann-Whitney U test. Meanwhile, the influenced factors were also analyzed.
  
  
  RESULTS
  The mean concentrations of fine particulate matters and ultrafine particles were (157.2 ± 142.8) μg/m³ and (25 018 ± 9 309) particles/cm³, respectively. The particles' number and mass concentrations in haze days were 1.27 times and 2.91 times higher than those in non-haze days, respectively. The mass concentrations of fine particulate matters in the self-monitoring site were higher than those in the nearest central monitoring sites, and the hourly-average concentrations of particles were significantly consistent with those at the commuter times. Meanwhile, the setting off of fireworks/firecrackers during the Spring Festival could lead to short-term increases of the particles' number and mass concentrations. When the wind speed was low and the related humidity was high, the concentrations of particulate matters were relatively high, and the mass concentrations of fine particulate matters were lagged about 1-2 d.
  
  
  CONCLUSIONS
  The level of the particulate matters in this area was high. Heavy traffic, setting off of fireworks/firecrackers and meteorological factors may be some of the main factors affecting the concentrations of the particulate matters in this area. Among those factors, the effect of setting off of fireworks/firecrackers didn't last long and the effect of the meteorological factors had a hysteresis effect.
authors.affiliation: Department of Occupational & Environmental Health Sciences, Peking University School of Public Health, Beijing 100191, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Ni
authors.forename: Xing-ying
authors.initials: XY
authors.lastname: Tu
authors.forename: Yi-dan
authors.initials: YD
authors.lastname: Zhu
authors.forename: Xin-biao
authors.initials: XB
authors.lastname: Guo
authors.forename: Fu-rong
authors.initials: FR
authors.lastname: Deng
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D006801:Humans; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter