Saharan dust and association between particulate matter and case-specific mortality: a case-crossover analysis in Madrid (Spain)

Environ Health. 2012 Mar 8;11:11. doi: 10.1186/1476-069X-11-11.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa, Northern
  • Air Pollutants / analysis
  • Air Pollutants / toxicity*
  • Cardiovascular Diseases / chemically induced
  • Cardiovascular Diseases / epidemiology
  • Cardiovascular Diseases / mortality*
  • Cerebrovascular Disorders / chemically induced
  • Cerebrovascular Disorders / epidemiology
  • Cerebrovascular Disorders / mortality*
  • Cities / epidemiology
  • Cross-Over Studies
  • Dust / analysis*
  • Humans
  • Particulate Matter / analysis
  • Particulate Matter / toxicity*
  • Respiratory Tract Diseases / chemically induced
  • Respiratory Tract Diseases / epidemiology
  • Respiratory Tract Diseases / mortality*
  • Seasons
  • Spain / epidemiology


  • Air Pollutants
  • Dust
  • Particulate Matter