title: Meteorological and urban landscape factors on severe air pollution in Beijing.
abstract: Air pollution gained special attention with the rapid development in Beijing. In January 2013, Beijing experienced extreme air pollution, which was not well examined. We thus examine the magnitude of air quality in the particular month by applying the air quality index (AQI), which is based on the newly upgraded Chinese environmental standard. Our finding revealed that (1) air quality has distinct spatial heterogeneity and relatively better air quality was observed in the northwest while worse quality happened in the southeast part of the city; (2) the wind speed is the main determinant of air quality in the city-when wind speed is greater than 4 m/sec, air quality can be significantly improved; and (3) urban impervious surface makes a contribution to the severity of air pollution-that is, with an increase in the fraction of impervious surface in a given area, air pollution is more severe. The results from our study demonstrated the severe pollution in Beijing and its meteorological and landscape factors. Also, the results of this work suggest that very strict air quality management should be conducted when wind speed less than 4 m/sec, especially at places with a large fraction of urban impervious surface.
  
  
  CONCLUSIONS
  Prevention of air pollution is rare among methods with controls on meteorological and urban landscape conditions. We present research that utilizes the latest air quality index (AQI) to compare air pollution with meteorological and landscape conditions. We found that wind is the major meteorological factor that determines the air quality. For a given wind speed greater than 4 m/sec, the air quality improved significantly. Urban impervious surface also contributes to the severe air pollution: that is, when the fraction of impervious surface increases, there is more severe air pollution. These results suggest that air quality management should be conducted when wind speed is less than 4 m/sec, especially at places with a larger fraction of urban impervious surface.
authors.affiliation: a State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing , People's Republic of China.
authors.forename: Lijian
authors.initials: L
authors.lastname: Han
authors.forename: Weiqi
authors.initials: W
authors.lastname: Zhou
authors.forename: Weifeng
authors.initials: W
authors.lastname: Li
authors.forename: Derege T
authors.initials: DT
authors.lastname: Meshesha
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Mingqing
authors.initials: M
authors.lastname: Zheng
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000032:analysis* / Q000517:prevention & control*; D002248:Carbon Monoxide / Q000032:analysis; D002681:China; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D009589:Nitrogen Oxides / Q000032:analysis; D010126:Ozone / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis; D011634:Public Health; D018531:Spacecraft; D013458:Sulfur Dioxide / Q000032:analysis; D013997:Time Factors; D014887:Weather
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D002248:Carbon Monoxide