Airborne dust absorption by semi-arid forests reduces PM pollution in nearby urban environments

Dust storms are a major source of global atmospheric particulate matter (PM), having significant impacts on air pollution and human health. During dust storms, daily averages of atmospheric PM concentrations can reach high levels above the World Health Organization (WHO) guideline for air quality. The objective of this study was to explore the impact of forests on PM distribution following dust events in a region that is subjected to frequent dust storms (Northern Negev, Israel). Dust was measured in a forest transect including urban environments that are nearby the forest and at a distal location. During a background period, without dust events, the forest with its surrounding areas were characterized by lower monthly average of PM concentrations (38 mu g/m(3)) compared with areas that are not affected by the forest (54 mu g/m(3)). Such difference can be meaningful for long-term human health exposure. A reduction in PM levels in the forest transect was evident at most measured dust events, depending on the storm intensity and the locations of the protected areas. A significant reduction in PM2.5/PM10 during dust events, indicates the high efficiency of the forest trees to absorb airborne PM2.5. Analysis of dust particles absorbed on the foliage revealed a total dust deposits of 8.1-92 g/m(2), which is equal to a minimum of 4182 tons removed from the atmosphere per a forest foliage area (30 km(2)). The findings can support environmental strategies to enhance life quality in regions that are subjected to dust storms, or under potential risk of dust-related PM due to land use and/or climate changes. (C) 2017 Elsevier B.V. All rights reserved.