Airborne particulate matter localisation in the human respiratory system

Respired particles accumulated in the epithelial regions of trachea and bro nchi were identified and characterised using micro-PIXE elemental mapping o f thin frozen sections carried out at the Oxford Nuclear Microprobe facilit y. Isolated particles with diameters of 2-10 mu m could be detected, mainly at the trachea epithelial surface. In bronchi respiratory mucosa, granular regions can also be observed that may correspond to particle agglomeration s (2-4 mu m diameters) and/or inclusions in macrophages. Particles, observe d in the upper regions of the respiratory tract consist mainly of earth cru st elements such as Al, Si, Ca and Fe. Occasionally, Ti and Zn are also pre sent. Particles observed in the bronchi have a more varied chemical composi tion. Elements such as V, Cr, Mn, Fe, Cu, Zn were detected, mainly in assoc iation with S, K, Ca or Si. (C) 1999 Elsevier Science B.V. All rights reser ved.