QUANTITATIVE PATHOLOGY OF NASAL PASSAGES IN RATS EXPOSED TO URBAN LEVELS OF AIR-POLLUTION

In order to assess the adverse effects of urban levels of air pollutio n, rats were used as biological indicators in a chronic exposure exper iment. Animals were housed for 6 months in the center of Sao Paulo (th e largest South American town) and compared to controls kept for the s ame period in a clean area. Pollution levels were obtained from a stat e air pollution monitoring station, 200 m distant from exposure locati on, which provided the levels of CO, SO2, particulates, and ozone. The nasal septum was submitted to quantitative analysis of morphological and histochemical parameters, comprising the measurement of volume of epithelium and lamina propria per unity of surface of basal lamina, th e amount of mucus stored in the surface epithelium, the volume densiti es of neutral and acidic mucus in the lamina propria glands, and the d ensities of secretory and ciliated cells in the epithelium. The result s obtained in the present investigation suggest that chronic exposure to urban levels of air pollution induces secretory hypertrophy, combin ed with a shift toward acidic mucus secretion and ciliary damage. The results are consistent with the idea that prolonged exposure to low le vels of air pollution deteriorates respiratory defenses against infect ious agents and may cause an increase in respiratory morbidity and per haps mortality. (C) 1994 Academic Press, Inc.