Subchronic DE Exposure Elevates α Synuclein in the Midbrain. Male Fischer 344 rats were exposed to either filtered air (control, 0 μg PM/m3 DE, n = 8), 35 μg PM/m3 DE (Low, n = 8), 100 μg PM/m3 DE (Mid Low, n = 8), 311 μg PM/m3 DE (Mid High, n = 8), or 992 μg PM/m3 DE (High, n = 8) for 6 months. α Synuclein protein levels were measured in the midbrain by western blot. An * indicates significant difference (p < 0.05) from control animals. DE elevated α synuclein protein levels in the midbrain at only the highest concentrations tested, demonstrating that subchronic exposure to high levels of air pollution is associated with Parkinson's disease-like pathology.