Short-term effects of particulate matter on total mortality during Saharan dust outbreaks: A case-crossover analysis in Madrid (Spain)

Background The role of Saharan dust outbreaks on the relationship between particulate matter and daily mortality has recently been addressed in studies conducted in Southern Europe, although they have not given consistent results. Methods We investigated the effects of coarse (PM10–2.5) and fine particulate matter (PM2.5) in Madrid on total mortality during Saharan dust and non-dust days using a case-crossover design. Results During Saharan dust days, an increase of 10 mg/m3 of PM10–2.5 raised total mortality by 2.8% compared with 0.6% during non-dust days (P-value for interaction = 0.0165). Conclusion We found evidence of stronger adverse health effects of PM10–2.5 during Saharan dust outbreaks effects for impacted European populations, but not for PM2.5. Further research is needed to understand mechanisms by which Saharan dust increases risk of mortality.