Ultrastructural alterations in the mouse lung caused by real-life ambient PM10 at urban traffic sites

Current levels of ambient air particulate matter (PM) are associated with mortality and morbidity in urban populations worldwide. Nevertheless, current knowledge does not allow precise quantification or definitive ranking of the health effects of individual PM components and indeed, associations may be the result of multiple components acting on different physiological mechanisms. In this paper, healthy Balb/c mice were exposed to ambient PM10 at a traffic site of a large city (Thessaloniki, northern Greece), in parallel to control mice that were exposed to filtered air. Structural damages were examined in ultrafine sections of lung tissues by Transmission Electronic Microscopy (TEM). Ambient PM10 samples were also collected during the exposure experiment and characterized with respect to chemical composition and oxidative potential. Severe ultrastructural alterations in the lung tissue after a 10-week exposure of mice at PM10 levels often exceeding the daily limit of Directive 2008/50/EC were revealed mainly implying PM-induced oxidative stress. The DTT-based redox activity of PM10 was found within the range of values reported for traffic sites being correlated with traffic-related constituents. Although linkage of the observed lung damage with specific chemical components or sources need further elucidation, the magnitude of biological responses highlight the necessity for national and local strategies for mitigation of particle emissions from combustion sources.