FIG. 8.

Intracellular localization of underground railway particulate matter (PM) in primary bronchial epithelial cell (PBEC) air-liquid interface (ALI) cultures after 24 h incubation. Healthy donor ALI cultures were incubated with coarse, fine, or ultrafine underground railway PM for 24 h, after which time they were washed, fixed, and embedded for transmission electron microscopy. At least eight ultrafine sections were viewed for each of two areas per culture, with areas at least 100 µm apart. No obvious differences were noted in quantity or localization of between PM size fractions. PM is shown free in the cytosol in proximity to a mitochondrion (A, treated with 3 µg/cm² coarse PM), within a membrane-bound vesicle (B, treated with 12 µg/cm² ultrafine PM), and apparently within a mitochondrion (C, treated with 3 µg/cm² coarse PM). No PM was observed within cell nuclei. Scale bar represents 500 nm.