All organisms have the ability to respond and adapt to a myriad of environmental insults.
The human respiratory epithelium, when exposed to oxidant gases in photochemical smog, is at risk of DNA damage and requires efficient cellular adaptative responses to resist the environmentally induced cell damage. Respiratory symptoms, nasal cytology and histopathology, cell viabilities, and single-cell gel electrophoresis were investigated. Atmospheric pollutant data were obtained from a fixed-site monitoring station. Thereafter, the number of cells with SSBs remained stable in spite of the continuous increase in cumulative ozone, suggesting a threshold for cumulative DNA nasal damage. Exposure to a polluted urban atmosphere induces SSBs in human nasal respiratory epithelium, and nasal SSBs could serve as a biomarker of ozone exposure.