Ozone pollution is a prominent public health issue, but there are few studies on the effect of ozone on the ultrastructure of respiratory system; we conducted this research. Exposed to 1.1 ppm O3 4 h per day, the mice lungs and bronchi were taken on the 15th or 30th day. The sections stained with HE and immunohistochemical streptavidin–peroxidase methods for NQO1, Nrf2, and Keap1 were observed and measured under the optical microscope. TEM was used for ultrastructure observation. The animals'

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... rums were detected for CRP and IL-6 levels. The HE-stained sections showed no obvious micromorphological changes in the O3 exposure, but the NQO1 average optical density was higher than the control on the 15th day (p < 0.05). The ultrastructural changes were found in the O3 exposure group, such as bulges and vacuoles in type I alveolar cells, the increased evacuation of substance from lamellar bodies in the type II alveolar cells, the increased space around the goblet nucleus, binuclear goblet, and columnar cells. CRP and IL-6 levels increased compared with the control (p < 0.05). Although inhaling 1.1 ppm O3 had no significant effect on the micromorphology of the mice lungs and bronchi, it did affect the ultrastructure with oxidative stress and inflammatory responses.