PM₁₀ levels at urban, suburban, and background locations in the eastern Mediterranean: local versus regional sources with emphasis on African dust

Abstract

PM₁₀ levels were determined at different locations in a coastal site in the eastern Mediterranean to assess the relative contribution of local versus regional sources. Two campaigns were conducted: during the first, PM₁₀ was monitored at three urban locations (kerbside/traffic/background) at different sampling periods, whereas during the second one, PM₁₀ was simultaneously measured at two locations (urban/suburban). Both campaigns have shown that African dust transport was a major carrier of coarse particles. Daily PM₁₀ concentrations of 547 μg m⁻³ and 234 μg m⁻³ were measured during the first and the second campaigns, respectively, both of them associated with severe dust storms. However, some dust episodes influenced lesser PM₁₀ levels. The contribution from dust episodes to the measured concentration was estimated at 2–527 μg m⁻³ during the first campaign and 4–218 μg m⁻³ during the second campaign. Classification into dusty and non-dusty days has shown that local anthropogenic sources also influence ambient PM₁₀ concentrations; however, few exceedances of the daily limit of 50 μg m⁻³ occurred during both campaigns. Particularly, it was found that domestic heating during cold months was a major contributor to PM₁₀ levels followed by emissions from traffic with higher contribution of the latter during summer months (high touristic season) as well as non-traffic emissions (road dust resuspension). Hourly average PM₁₀ concentration during the second campaign has shown that traffic-related emissions and/or road dust resuspension were associated with up to 40 μg m⁻³ whereas during wintertime late evening hours, PM₁₀ concentration from heating reached up to 60 μg m⁻³ at the central urban location.