Abstract
Air pollution has many adverse effects on health and is associated with an increased risk of mortality. Desert dust outbreaks contribute directly to air pollution by increasing particulate matter concentrations. We investigated the influence of desert dust outbreaks on air quality in Santa Cruz de Tenerife, a city located in the dust export pathway off the west coast of North Africa, using air-quality observations from a six-year period (2012–2017). During winter intense dust outbreaks PM 10 mean (24-h) concentrations increased from 14 μ g m − 3 to 98 μ g m − 3 , on average, and PM 2 . 5 mean (24-h) concentrations increased from 6 μ g m − 3 to 32 μ g m − 3 . Increases were less during summer outbreaks, with a tripling of PM 10 and PM 2 . 5 daily mean concentrations. We found that desert dust outbreaks reduced the height of the marine boundary layer in our study area by >45%, on average, in summer and by ∼25%, on average, in winter. This thinning of the marine boundary layer was associated with an increase of local anthropogenic pollution during dust outbreaks. NO 2 and NO mean concentrations more than doubled and even larger relative increases in black carbon were observed during the more intense summer dust outbreaks; increases also occurred during the winter outbreaks but were less than in summer. This has public health implications; local anthropogenic emissions need to be reduced even further in areas that are impacted by desert dust outbreaks to reduce adverse health effects.
Highlights
It is well known that air pollution has many adverse effects on health [1,2], and recent research suggests substantially higher health impacts than previously assumed, with a near doubling of the global mortality rate attributable to ambient air pollution to 8.8 million [3]
Data for 2015 illustrates how all episodes of increased PM10 and PM2.5 concentrations and all the exceedances of the WorldHealth Organisation (WHO) 24-h mean PM10 (50 μg m−3 ) and PM2.5 (25 μg m−3 ) Air-Quality Guideline occur during dust outbreak days (Figure 2a,b)
To assess the indirect influence of desert dust outbreaks on air quality in urban areas, we use data of the marine boundary layer height (BLH) obtained from radiosonde observations and from a numerical weather prediction model
Summary
It is well known that air pollution has many adverse effects on health [1,2], and recent research suggests substantially higher health impacts than previously assumed, with a near doubling of the global mortality rate attributable to ambient air pollution to 8.8 million [3]. Health Organisation (WHO) sets Air-Quality Guidelines (AQGs) for particulate matter (PM10 and PM2.5 ), sulphur dioxide (SO2 ), nitrogen dioxide (NO2 ), and ozone (O3 ) [6]. 91% of the world’s population and 93% of children live in environments with air-pollution levels exceeding the WHO guidelines [4,7]. Desert dust outbreaks contribute directly to air pollution by increasing particulate matter concentrations, often by orders of magnitude [8,9,10]. Airborne desert dust impacts air quality on both local and global scales as dust can be transported thousands of km in the atmosphere [11]; Atmosphere 2020, 11, 23; doi:10.3390/atmos11010023 www.mdpi.com/journal/atmosphere
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