Short-term effects of particulate matter and desert dust on mortality in Southern Europe, the Middle East and Eastern Asia

Abstract

Background: Desert dust represents a threat to health, but the evidence is limited, as past studies were localised and adopted different exposure metrics and/or statistical approaches. We aim to evaluate the short-term effects of desert dust episodes and particulate matter (PM) on natural mortality in multiple cities from different geo-climatic zones. Methods: Daily death counts were collected for 21 cities in southern Europe (France, Greece, Italy, Portugal, Spain), the Middle East (Iran, Kuwait) and Eastern Asia (China, Japan, South Korea, Taiwan) from 2003-2018. Dust advection days were identified using satellite data, operational models and back-trajectories. Daily mean concentrations of PM10 (PM<10µm) and PM2.5 (<2.5µm) were available for 21 and 16 cities, respectively. City-specific quasi-Poisson regression models were fitted, adjusted for time trends and meteorology, and city-specific estimates were combined using random-effects meta-analysis. Results: The frequency of dust days ranged from 5% in Northern Italy to 61% in Northern China, with highest levels of PM10 and PM2.5 raised in Kuwait (191 µg/m3) and Xian (182 µg/m3). Overall, dust (yes/no), PM10 and PM25 (10 µg/m3) increased mortality at the same day by 0.52% (95% confidence interval: 0.04, 1.01), 0.14% (0.07,0.21) and 0.16% (0.02, 0.31), respectively. We found differential effects of PM on non-dust versus dust days: on non-dust days 10 µg/m3 increases in PM10 and PM25 increased mortality by 0.20% (0.11, 0.29) and 0.26% (0.05, 0.46) in non-dust days, while in dust days they increased mortality by 0.06% (95% confidence interval: 0.01, 0.10) and 0.05% (-0.04, 0.15), respectively. Conclusions: Desert dust may have independent adverse health effects. Further investigation is needed to disentangle the complex role of dust on air quality and health. On-going analyses on a broader set of cities within the MCC network provide a promising opportunity for this purpose. Key words: Desert dust; particulate matter; short-term effects; mortality