Approximately, 20 % of particulate and aerosol emissions into the urban atmosphere are of natural origin (including wildfires and Saharan dust). During these natural episodes, PM10 and PM2.5 levels usually exceed World Health Organisation (WHO) health protection thresholds. This study sought to evaluate the possible effect of advections of particulate matter from biomass fuel combustion on daily specific-cause mortality among the general population and the segment aged a parts per thousand yen75 years in Madrid. Ecological time-series study in the city of Madrid from January 01, 2004 to December 31, 2009. The dependent variable analysed was daily mortality due to natural (ICD-10:A00-R99), circulatory (ICD-10:I00-I99), and respiratory (ICD-10:J00-J99) causes in the population, both general and aged a parts per thousand yen75 years. The following independent and control variables were considered: a) daily mean PM2.5 and PM10 concentrations; b) maximum daily temperature; c) daily mean O-3 and NO2 concentrations; d) advection of particulate matter from biomass combustion (), using a dichotomous variable and e) linear trend and seasonalities. We conducted a descriptive analysis, performed a test of means and, to ascertain relative risk, fitted a model using autoregressive Poisson regression and stratifying by days with and without biomass advection, in both populations. Of the 2192 days analysed, biomass advection occurred on 56, with mean PM2.5 and PM10 values registering a significant increase during these days. PM10 had a greater impact on organic mortality with advection (RRall ages = 1.035 [1.011-1.060]; RR a parts per thousand yenaEuro parts per thousand 75 years = 1.066 [1.031-1.103]) than did PM2.5 without advection (RRall ages = 1.017 [1.009-1.025]; RR a parts per thousand yenaEuro parts per thousand 75 years = 1.012 [1.003-1.022]). Among specific causes, respiratory-though not circulatory-causes were associated with PM10 on days with advection in a parts per thousand yen75 year age group. PM10, rather than PM2.5, were associated with an increase in natural cause mortality on days with advection of particulate matter from biomass combustion, particularly in the a parts per thousand yen75 year age group.
