title: Temperature modifies the acute effect of particulate air pollution on mortality in eight Chinese cities.
abstract: BACKGROUND
  Both temperature and particulate air pollution are associated with increased death risk. However, whether the effect of particulate air pollution on mortality is modified by temperature remains unsettled.
  
  
  METHODS
  A stratified time-series analysis was conducted to examine whether the effects of particulate matter less than 10 μm in aerodynamic diameter (PM(10)) on mortality was modified by temperature in eight Chinese cities. Poisson regression models incorporating natural spline smoothing functions were used to adjust for long-term and seasonal trends of mortality, as well as other time-varying covariates. The bivariate response surface model was applied to visually examine the potential interacting effect. The associations between PM(10) and mortality were stratified by temperature to examine effect modification.
  
  
  RESULTS
  The averaged daily concentrations of PM(10) in the eight Chinese cities ranged from 65 μg/m(3) to 124 μg/m(3), which were much higher than in Western countries. We found evidence that the effects of PM(10) on mortality may depend on temperature. The eight-city combined analysis showed that on "normal" (5th-95th percentile) temperature days, a 10-μg/m(3) increment in PM(10) corresponded to a 0.54% (95% CI, 0.39 to 0.69) increase of total mortality, 0.56% (95% CI, 0.36 to 0.76) increase of cardiovascular mortality, and 0.80% (95% CI, 0.64 to 0.96) increase of respiratory mortality. On high temperature (>95th percentile) days, the estimates increased to 1.35% (95% CI, 0.80 to 1.91) for total mortality, 1.57% (95% CI, 0.69 to 2.46) for cardiovascular mortality, and 1.79% (95% CI, 0.75 to 2.83) for respiratory mortality. We did not observe significant effect modification by extreme low temperature.
  
  
  CONCLUSIONS
  Extreme high temperature increased the associations of PM(10) with daily mortality. These findings may have implication for the health impact associated with both air pollution and global climate change.
authors.affiliation: School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Meng
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zhuohui
authors.initials: Z
authors.lastname: Zhao
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Duan
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Xu
authors.forename: Haidong
authors.initials: H
authors.lastname: Kan
mesh_terms: D000208:Acute Disease; D002318:Cardiovascular Diseases / Q000401:mortality; D002681:China / Q000453:epidemiology; D006801:Humans; D008954:Models, Biological; D009026:Mortality; D052638:Particulate Matter / Q000009:adverse effects*; D012140:Respiratory Tract Diseases / Q000401:mortality; D012621:Seasons; D013696:Temperature
chemical_list: D052638:Particulate Matter