Fig. 4

Formation of ROS by ozone exposure was assessed based on the fold induction of the fluorescein intensity using the 2′,7′-dichlorodihydrofluorescein diacetate reagent, which was calculated as the fluorescein intensities of distilled deionized water and PM dissolved in solution with bubbling through 0.12 ppm and 0.24 ppm ozone for 1 min, 5 min, and 15 min divided by those without bubbling through ozone. a Generation of ROS by ozone in collected PM dissolved in solution. b Generation of ROS by ozone in distilled deionized water. Bars represent means ± SD