Health Impacts Estimation of Mineralogical and Chemical Characterization of Suspended Atmospheric Particles over the East Desert

Abstract

Problem statement: The small size fraction of aerosols, measured as PM10 and PM2.5, rather than the larger particles, is considered to be responsible for most of the health effects. Such particles have a relatively long residence time in the atmosphere and can therefore travel over long distances. Hence, a large portion of ambient concentrations of PM₁₀ and in particular of particles with an aerodynamic diameter less than 2.5 µm (PM_2.5), can be attributed to long range trans boundary air pollution or to other remote sources. The estimates of exposure and of health effects are based on a number of uncertain assumptions and data sets, as described in previous article. Approach: In industrialized Middle East countries, the daily deposition of PM₁₀ particles in the lungs is roughly 250 μg day⁻¹, which represents a small dose in terms of traditional toxicology studies. Studies of PM₁₀ have considered this total material but have not asked how much its chemical or physical characteristics contribute to its total toxicity. Results: This article focuses on the description of the present knowledge on PM₁₀ concentration fields and predominant sources contributing to PM₁₀ from long range transport of pollution. PM₁₀ is a complex mixture of many known and unknown components; therefore, a short introduction on the composition of PM₁₀ is given. The studies denote to the African dust from mean PM₁₀ levels background levels are still 5-10 mg m³ higher in the Eastern Basin (EMB) when compared with those in the Western (WMB), mainly due to the higher anthropogenic and sea spray loads. Conclusion: As regards for the seasonal trends, these are largely driven by the occurrence of African dust events, resulting in a spring-early summer maximum over the EMB and a clear summer maximum in the WMB, although in this later region the recirculation of aged air masses play an important role. Furthermore, a marked seasonal trend is still evident when subtracting the African dust load. This is characterized by a high summer maximum (driven by low precipitation, high isolation) and a winter minimum (intense synoptic winds).