title: Estimated acute effects of ambient ozone and nitrogen dioxide on mortality in the Pearl River Delta of southern China.
abstract: OBJECTIVE
  Epidemiologic studies have attributed adverse health effects to air pollution; however, controversy remains regarding the relationship between ambient oxidants [ozone (O₃) and nitrogen dioxide (NO₂)] and mortality, especially in Asia. We conducted a four-city time-series study to investigate acute effects of O₃ and NO₂ in the Pearl River Delta (PRD) of southern China, using data from 2006 through 2008.
  
  
  METHODS
  We used generalized linear models with Poisson regression incorporating natural spline functions to analyze acute mortality in association with O₃ and NO₂, with PM₁₀ (particulate matter ≤ 10 μm in diameter) included as a major confounder. Effect estimates were determined for individual cities and for the four cities as a whole. We stratified the analysis according to high- and low- exposure periods for O₃.
  
  
  RESULTS
  We found consistent positive associations between ambient oxidants and daily mortality across the PRD cities. Overall, 10-μg/m³ increases in average O₃ and NO₂ concentrations over the previous 2 days were associated with 0.81% [95% confidence interval (CI): 0.63%, 1.00%] and 1.95% (95% CI: 1.62%, 2.29%) increases in total mortality, respectively, with stronger estimated effects for cardiovascular and respiratory mortality. After adjusting for PM₁₀, estimated effects of O₃ on total and cardiovascular mortality were stronger for exposure during high-exposure months (September through November), whereas respiratory mortality was associated with O₃ exposure during nonpeak exposure months only.
  
  
  CONCLUSIONS
  Our findings suggest significant acute mortality effects of O₃ and NO₂ in the PRD and strengthen the rationale for further limiting the ambient pollution levels in the area.
authors.affiliation: SKJ Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, and Centre for Environment and Health, Peking University, Beijing, China.
authors.forename: Yebin
authors.initials: Y
authors.lastname: Tao
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Huang
authors.forename: Liuju
authors.initials: L
authors.lastname: Zhong
authors.forename: Shou-En
authors.initials: SE
authors.lastname: Lu
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Lingzhen
authors.initials: L
authors.lastname: Dai
authors.forename: Yuanhang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
mesh_terms: D002318:Cardiovascular Diseases / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality*; D002681:China / Q000453:epidemiology; D002947:Cities / Q000453:epidemiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity*; D010083:Oxidants, Photochemical / Q000032:analysis / Q000633:toxicity*; D010126:Ozone / Q000032:analysis / Q000633:toxicity*; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity; D012140:Respiratory Tract Diseases / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality*; D013997:Time Factors
chemical_list: D010083:Oxidants, Photochemical; D052638:Particulate Matter; D010126:Ozone; D009585:Nitrogen Dioxide