title: Respiratory effects of indoor particles in young children are size dependent.
abstract: BACKGROUND
  Extensive epidemiological studies have provided evidence of an association between elevated outdoor particulate air pollution and adverse health effects. However, while people typically spend majority of time indoors, there is limited knowledge on airborne indoor particles and on the correlation between the concentrations of indoor particles and health effects. Even insights into the influence of differently sized indoor particles on human health are still rare.
  
  
  OBJECTIVE
  The association between differentially sized indoor air particles and the development of respiratory diseases was studied for three year aged children.
  
  
  METHODS
  Short-term measurements of particle mass and number concentrations were carried out in children's rooms. Information on possible particle sources (smoking habits, type of heating, and traffic) and respiratory outcomes were obtained from questionnaires. Measured indoor particle concentrations were correlated with possible sources of indoor particles and with respiratory health impacts.
  
  
  RESULTS
  Daily smoking, smoking more than 5 cigarettes per day at home and traffic density in front of the window of children's room were found to be related to indoor exposure by particles of different diameters. High indoor particle exposures were associated with an increased risk for the development of obstructive bronchitis and in some extent of non-obstructive bronchitis. The strongest impact was observed for the mass concentration of particles <1 μm and the number concentration of particles >0.5 μm. The risk increases still remain significant if tested for stability changing the number of adjustment variables or omitting randomly selected cases, respectively.
  
  
  CONCLUSIONS
  Our results show significant associations between indoor particle concentrations and the risks for respiratory diseases in young children. The applied short-term measurements can help to assess the health risks of indoor particles with different sizes within epidemiological studies.
authors.affiliation: Helmholtz Centre for Environmental Research-UFZ, Core Facility Studies, Permoserstraße 15, 04318 Leipzig, Germany. ulrich.franck@ufz.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Franck
authors.forename: Olf
authors.initials: O
authors.lastname: Herbarth
authors.forename: Stefan
authors.initials: S
authors.lastname: Röder
authors.forename: Uwe
authors.initials: U
authors.lastname: Schlink
authors.forename: Michael
authors.initials: M
authors.lastname: Borte
authors.forename: Ulrike
authors.initials: U
authors.lastname: Diez
authors.forename: Ursula
authors.initials: U
authors.lastname: Krämer
authors.forename: Irina
authors.initials: I
authors.lastname: Lehmann
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity; D016902:Air Pollution, Indoor / Q000032:analysis / Q000706:statistics & numerical data*; D002675:Child, Preschool; D015331:Cohort Studies; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012140:Respiratory Tract Diseases / Q000453:epidemiology*
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter