Elemental analysis of aerosols in Tehran's atmosphere using PIXE and identification of pollution sources.

In this study, the proton-induced X-ray emission (PIXE) technique has been applied to measure the elemental composition and concentrations of particulate matter of 220 samples of aerosols in Tehran's atmosphere within a 450-day time interval starting from March 2009 and ending in June 2010, covering all four seasons. PIXE analysis shows the samples are comprised of various elements including Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. Also, to obtain more information about the sources of pollution and to identify the major sources of urban particulate matter, principal component analysis (PCA) was used. Furthermore, micro-PIXE was performed to study individual aerosols in some samples. Results revealed that the concentration of elements originating from vehicle emissions increases three times in winter; whereas the concentration of elements with soil origin remains constant. Based on wind rose maps, it is inferred that the high concentrations of the elements Al, Si, K, Ca, Ti, Mn, and Fe are associated with natural dust brought by winds into Tehran from the west.

Feasibility of breast cancer screening by PIXE analysis of hair.

To reveal the role of key elements present in the hair of breast cancer patients on cancer development, the levels of a number of elements in scalp hair samples of 82 people including healthy individuals, people suffering from benign breast disease, and breast cancer patients were measured by PIXE analysis. Pellets of hair samples were prepared and bombarded by 2.2 MeV proton beam of a 3-MV Van de Graaff accelerator. The number of incident ions hitting the sample was indirectly measured using the RBS spectrum of a thin Ag film placed in the beam path. The concentrations of S, Cl, K, Ca, Fe, and Cu in the hair of healthy individuals were in agreement with those observed in the hair of hyperplasia and cancer patients within standard deviations. However, a lower average level of zinc was found in samples from hyperplasia and breast cancer patients. Strong positive correlations were found between iron and potassium as well as between calcium and potassium in the cancer patients. These results could be of significance in the screening for breast cancer.