Fig. 2

The distribution of circulatory cGMP and Tail DNA percent in study subjects with different internal diesel exhaust exposure. Study subjects were categorized into three groups including low, medium, and high according to their internal exposure to diesel exhaust. Dose–response were identified between exposure category and levels of cGMP and tail DNA percent. The five horizontal bars from bottom to top represent the minimum, first quartile, median, third quartile, and maximum. Symbol “◊” represents mean value