title: Short-term mortality rates during a decade of improved air quality in Erfurt, Germany.
abstract: BACKGROUND
  Numerous studies have shown associations between ambient air pollution and daily mortality.
  
  
  OBJECTIVE
  Our goal was to investigate the association of ambient air pollution and daily mortality in Erfurt, Germany, over a 10.5-year period after the German unification, when air quality improved.
  
  
  METHODS
  We obtained daily mortality counts and data on mass concentrations of particulate matter (PM)<10 microm in aerodynamic diameter (PM10), gaseous pollutants, and meteorology in Erfurt between October 1991 and March 2002. We obtained ultrafine particle number concentrations (UFP) and mass concentrations of PM<2.5 microm in aerodynamic diameter (PM2.5) from September 1995 to March 2002. We analyzed the data using semiparametric Poisson regression models adjusting for trend, seasonality, influenza epidemics, day of the week, and meteorology. We evaluated cumulative associations between air pollution and mortality using polynomial distributed lag (PDL) models and multiday moving averages of air pollutants. We evaluated changes in the associations over time in time-varying coefficient models.
  
  
  RESULTS
  Air pollution concentrations decreased over the study period. Cumulative exposure to UFP was associated with increased mortality. An interquartile range (IQR) increase in the 15-day cumulative mean UFP of 7,649 cm(-3) was associated with a relative risk (RR) of 1.060 [95% confidence interval (CI), 1.008-1.114] for PDL models and an RR/IQR of 1.055 (95% CI, 1.011-1.101) for moving averages. RRs decreased from the mid-1990s to the late 1990s.
  
  
  CONCLUSIONS
  Results indicate an elevated mortality risk from short-term exposure to UFP. They further suggest that RRs for short-term associations of air pollution decreased as pollution control measures were implemented in Eastern Germany.
authors.affiliation: Institute of Epidemiology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany. susanne.breitner@helmholtz-muenchen.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Breitner
authors.forename: Matthias
authors.initials: M
authors.lastname: Stölzel
authors.forename: Josef
authors.initials: J
authors.lastname: Cyrys
authors.forename: Mike
authors.initials: M
authors.lastname: Pitz
authors.forename: Gabriele
authors.initials: G
authors.lastname: Wölke
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kreyling
authors.forename: Helmut
authors.initials: H
authors.lastname: Küchenhoff
authors.forename: Joachim
authors.initials: J
authors.lastname: Heinrich
authors.forename: H-Erich
authors.initials: HE
authors.lastname: Wichmann
authors.forename: Annette
authors.initials: A
authors.lastname: Peters