title: Saharan dust and association between particulate matter and case-specific mortality: a case-crossover analysis in Madrid (Spain).
abstract: BACKGROUND
  Saharan dust intrusions are a common phenomenon in the Madrid atmosphere, leading induce exceedances of the 50 μg/m(3)--EU 24 h standard for PM10.
  
  
  METHODS
  We investigated the effects of exposure to PM(10) between January 2003 and December 2005 in Madrid (Spain) on daily case-specific mortality; changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design.
  
  
  RESULTS
  Saharan dust affected 20% of days in the city of Madrid. Mean concentration of PM(10) was higher during dust days (47.7 μg/m(3)) than non-dust days (31.4 μg/m(3)). The rise of mortality per 10 μg/m(3) PM(10) concentration were always largely for Saharan dust-days. When stratifying by season risks of PM(10), at lag 1, during Saharan dust days were stronger for respiratory causes during cold season (IR% = 3.34% (95% CI: 0.36, 6.41) versus 2.87% (95% CI: 1.30, 4.47)) while for circulatory causes effects were stronger during warm season (IR% = 4.19% (95% CI: 1.34, 7.13) versus 2.65% (95% CI: 0.12, 5.23)). No effects were found for cerebrovascular causes.
  
  
  CONCLUSIONS
  We found evidence of strongest effects of particulate matter during Saharan dust days, providing a suggestion of effect modification, even though interaction terms were not statistically significant. Further investigation is needed to understand the mechanism by which Saharan dust increases mortality.
authors.affiliation: National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Díaz
authors.forename: Aurelio
authors.initials: A
authors.lastname: Tobías
authors.forename: Cristina
authors.initials: C
authors.lastname: Linares
mesh_terms: D000352:Africa, Northern; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D002318:Cardiovascular Diseases / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality*; D002561:Cerebrovascular Disorders / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality*; D002947:Cities / Q000453:epidemiology; D018592:Cross-Over Studies; D004391:Dust / Q000032:analysis*; D006801:Humans; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity*; D012140:Respiratory Tract Diseases / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality*; D012621:Seasons; D013030:Spain / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D004391:Dust; D052638:Particulate Matter