title: Effects of air pollution on neonatal prematurity in Guangzhou of China: a time-series study.
abstract: BACKGROUND
  Over the last decade, a few studies have investigated the possible adverse effects of ambient air pollution on preterm birth. However, the correlation between them still remains unclear, due to insufficient evidences.
  
  
  METHODS
  The correlation between air pollution and preterm birth in Guangzhou city was examined by using the Generalized Additive Model (GAM) extended Poisson regression model in which we controlled the confounding factors such as meteorological factors, time trends, weather and day of the week (DOW). We also adjusted the co linearity of air pollutants by using Principal Component Analysis. The meteorological data and air pollution data were obtained from the Meteorological Bureau and the Environmental Monitoring Centre, while the medical records of newborns were collected from the perinatal health database of all obstetric institutions in Guangzhou, China in 2007.
  
  
  RESULTS
  In 2007, the average daily concentrations of NO₂, PM₁₀ and SO₂ in Guangzhou, were 61.04, 82.51 and 51.67 μg/m³ respectively, where each day an average of 21.47 preterm babies were delivered. Pearson correlation analysis suggested a negative correlation between the concentrations of NO₂, PM₁₀, SO₂, and temperature as well as relative humidity. As for the time-series GAM analysis, the results of single air pollutant model suggested that the cumulative effects of NO₂, PM₁₀ and SO₂ reached its peak on day 3, day 4 and day 3 respectively. An increase of 100 μg/m³ of air pollutants corresponded to relative risks (RRs) of 1.0542 (95%CI: 1.0080 ~1.1003), 1.0688 (95%CI: 1.0074 ~1.1301) and 1.1298 (95%CI: 1.0480 ~1.2116) respectively. After adjusting co linearity by using the Principal Component Analysis, the GAM model of the three air pollutants suggested that an increase of 100 μg/m³ of air pollutants corresponded to RRs of 1.0185 (95%CI: 1.0056~1.0313), 1.0215 (95%CI: 1.0066 ~1.0365) and 1.0326 (95%CI: 1.0101 ~1.0552) on day 0; and RRs of the three air pollutants, at their strongest cumulative effects, were 1.0219 (95%CI: 1.0053~1.0386), 1.0274 (95%CI: 1.0066~1.0482) and 1.0388 (95%CI: 1.0096 ~1.0681) respectively.
  
  
  CONCLUSIONS
  This study indicates that the daily concentrations of air pollutants such as NO₂, PM₁₀ and SO₂ have a positive correlation with the preterm births in Guangzhou, China.
authors.affiliation: College of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, PR China. zqgfrost@126.com
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Zhao
authors.forename: Zhijiang
authors.initials: Z
authors.lastname: Liang
authors.forename: Shijuan
authors.initials: S
authors.lastname: Tao
authors.forename: Juan
authors.initials: J
authors.lastname: Zhu
authors.forename: Yukai
authors.initials: Y
authors.lastname: Du
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity; D010323:Passive Cutaneous Anaphylaxis; D016012:Poisson Distribution; D011247:Pregnancy; D047928:Premature Birth / Q000139:chemically induced* / Q000453:epidemiology; D012307:Risk Factors; D013458:Sulfur Dioxide / Q000032:analysis / Q000633:toxicity; D014504:Urban Health
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide