Fig. 4From: Association between elevated serum bilirubin levels with preserved lung function under conditions of exposure to air pollutiona Estimated mean levels of FEV1 in low versus moderate and high levels of bilirubin to NOx adjusted for age, sex, BMI, diabetes, and smoking. FEV1 forced expiratory volume in 1 s, Nox nitrogen oxide, BMI body mass index. Y axis—mean level of FEV1 percent of predictive values. X axis—bilirubin level (mg/dL) divided according to low, moderate, and high serum bilirubin; 0.1–0.59 mg/dL, 0.6–0.8 mg/dL and 0.81–1.47 mg/dL, respectively. Gray line: low NOx level 0.4–14.0 ppm; Black line: 14.1–22.1 ppm and 22.2–33.5 ppm. b Estimated mean levels of FEV1 in low versus moderate and high levels of exposure to CO adjusted for age, sex, BMI, diabetes, and smoking. FEV1 forced expiratory volume in 1 s, CO carbon monoxide, BMI body mass index. Y axis—mean level of FEV1 percent of predictive values. X axis—bilirubin level (mg/dL) divided according to low, moderate, and high serum bilirubin; 0.1–0.59 mg/dL, 0.6–0.8 mg/dL and 0.81–1.47 mg/dL, respectively. Gray line: low CO level 0.1–0.7 ppm; Black line: 0.8–0.9 ppm and 1–1.2 ppmBack to article page