African dust outbreaks database
PROJECT STRUCTURE. ACTIVITIES AND RESEARCH LINES:
1. Analyze the database of identified transport episodes of African dust to the different national territory MAPAMA sectors during the study temporal range 2011-2015. The database is composed also by estimated values of daily contribution of African dust to the PM10 y PM2.5; levels (Figure III) for each event, yielded from a specific methodology developed ad hoc. This analysis will provide a list of African events with impact in the Madrid urban area within the study time range, classified by its intensity (weak, moderate or severe) based on contribution values of African dust.
Figure III. Diagram showing the relative size of particulate matter (PM10 y PM2.5) in relation with the size of human hair and beach sand grains. Source:US EPA (2008). Particulate Matter (PM) basics (online). https://www.epa.gov/pm-pollution/particulate-matter-pm-basics. Accessed 11 octubre 2017.
2. Perform a literature review of published studies in high-impact scientific journals related with extreme atmospheric events, mainly centered in the Mediterranean basin, as well as adverse effect on living beings. An special emphasis will be put in transport events of African dust and its effect on health of people living in highly–populated urban areas, but an assessment on the state-of-the-art of other types of extreme atmospheric events like heatwaves and forest fires.
This task will be performed with the support of the researchers Rocío Carmona, Cristina Linares and Julio Díaz, researchers from the Department of Epidemiology and Biostatistic, National School of Public Health, Carlos III National Institute of Health ,expertise in ambient factors impact on morbidity and mortality in urban areas.
Analysis of meteorological radiosoundings
3. Analysis of meteorological radiosoundings (Figure IV) launched daily at 12 UTC from the Barajas airport by AEMET, and the database of vertical profiles of optical properties provided by a lidar system belonging to the METALAB laboratory at CIEMAT (Figure V).
Figure IV. CIEMAT researchers preparing to carry out a meteorological radiosounding on July 1988, in Soto del Real (Madrid)
Figure V. CIEMAT lidar station
The analysis of vertical profiles of meteorological parameters provided by radiosoundings will allow an estimation of the mixing layer height (Figure VI), which determines the concentration levels reached by atmospheric pollutants on surface. The lower the mixing layer height, the higher the atmospheric pollutants concentration from local sources in urban areas. The analysis of vertical profiles of optical properties like backscattering coefficient, extinction coefficient or lidar ratio, will allow the characterization of aerosol-rich aloft layers along with its temporal evolution and calculate the aerosol microphysical properties in order to classify them during the African events of variable intensity that occurred within the study time range.
Figure VI. Diagram showing the relationship between the mixing layer depth and the concentration of atmospheric pollutants. The lower the mixing layer depth, the higher the concentration of air pollutants to which population in urban areas are exposed. The upper thermal inversion prevents the air pollutants from dispersing above its base. Adapted from: Ahrens, C.D., 1999. “Meteorology today: an introduction to weather, climate and the environment”. 6th ed. ISBN: 0-534-37201-5.
4. Statistical analysis of atmospheric pollutants (particles and gases) levels variations monitored in relevant sites for Madrid, provided by air quality network stations (Madrid city council, regional community council, EMEP European network for transboundary air pollution evaluation) during the evolution of African events of different intensity. From the analysis of the above-mentioned databases, the aim is identify statistically-significant relationships between the occurrence of African episodes of different intensities and the meteorological variables provided by radiosoundings and lidar system, that yield an increase of atmospheric pollutants on surface. This will imply that the occurrence of dust-rich aloft layers interfere with the mixing layer evolution and its final height by a series of mechanisms to be determined, which produce foreseeably an increase in particles and gases concentration on surface.
5. Epidemiologic analysis of temporal series of INE mortality values by different available causes for the study temporal range in Madrid, taking into account the occurrence of African events of variable intensity. Estimations of increase of relative risk of mortality in Madrid due to exposition to atmospheric pollutants during African events of different intensity.
This task will be performed with the support of the researchers Aurelio Tobías and Marco Pandolfi from the Institute of Environmental Assessment and Water Research (IDAEA-CSIC), expertise in African dust long-range transport events' studies, and their effects on air quality and health.
Identification of sinergistic effects
6. Identification of any type of positive synergy or interaction between the levels of atmospheric pollutants to which the Madrid population is exposed, and the occurrence of transport events of African mineral dust, will allow to assess the negative effect, not considered so far, of the climate change over the air quality of south European urban areas. It is foreseen the distribution of relevant results of the project in air quality and climate change websites, attendance to congresses and specialist meetings and preparation and publication in peer-reviewed scientific journals.
7. In the last stage of the project, an informative meeting about "the impact on health of extreme atmospheric events exacerbated by climate change", will be hosted at the CIEMAT premises and it will last 1 day.