Saharan dust and the impact on adult and elderly allergic patients: the effect of threshold values in the northern sector of Gran Canaria, Spain

Abstract

Gran Canaria Island is frequently impacted by Saharan dust, a health hazard of particular concern to the island population and health agencies. Airborne mineral dust has the severest impact on the higher age groups of the population, and those with respiratory conditions; despite that, on average, the ambient particulate matter (PM) concentrations fall within international PM guidelines. During 2010 and 2011, an epidemiological survey, in parallel with an air quality study, was conducted at the Dr Negrín hospital in Gran Canaria. This included the quarterly monitoring of outpatients and recording of emergency patients with respiratory diseases, together with the measurement of aerosol, meteorological, and PM-related air quality levels. The finer more toxic particles were collected with PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) aerosol samplers. The filter samples were gravimetrically and chemically analyzed for their elemental, water-soluble ions, carbon, and mineralogical contents. Individual particle morphology was measured by Scanning Electron Microscopy. Statistical analysis of the chemical and clinical data included the analysis of variance and calculation of Spearman correlation coefficients. No statistically significant relations were found between the allergic control group, the emergency room admissions, pulmonary conditions, medication, and elevated Saharan dust levels. However, changing environmental conditions, such as an increase in humidity or a reduction in ambient air temperature made a significant difference to the outcomes recorded on the health statements of the allergic and respiratory illness groups of the Gran Canary population.

Keywords:

• Natural mineral particles (NMP)
• Saharan dust geochemistry
• epidemiology
• allergic patients
• Canary Islands

Acknowledgments

This paper presents part of the research from the project ‘Textural and mineralogical characterization of NMPs and their health effect on the Canarian Population’ (PI2007/042) funded by the Canary Government and European Regional Development Fund. We thank NOAA and the Barcelona Supercomputing Centre-AEMET for the use of their back trajectory model and synoptic charts. We are grateful to the Canary Government Air Quality Network for the information on their website. We also thank the two anonymous referees for reading the manuscript and their constructive comments.