Fig. 2

Population attributable fraction (PAF) among selected risk factors. PAF, the proportion of cases that are attributable to a risk factor and could be prevented by modifying or eliminating the risk factor, is shown on the y-axis. The x-axis represents the risk factor exposure prevalence. The points on the graph reflect the relationship of exposure prevalence and PAF. The PAF is dependent on the prevalence of exposure and its odds ratio for asthma. The size of the points are proportional to prevalence. Odds ratios from meta-analyses were used to estimate PAF (Additional file 1: Table S1 and Fig. 1). References used to determine exposure prevalence for this figure: smoking, secondhand [71]; gas stove cooking [109]; physical activity, inadequate [110]; pets, cats [111]; probiotics [112]; omega-3 fatty acids [112]; H. pylori [113]; pets, dogs [111]; food sensitization, ≤ 2 years [114]; rhinovirus induced wheezing, ≤ 3 years [29, 30]; obesity [61]; overweight [115]; traffic pollution [116]; allergic rhinitis, mold [117]; fruit intake, adequate [118]; vegetable intake, adequate [118]; RSV infection, infant [28]; acetaminophen, infant [119]; antibiotic use, infant [42]; breastfeeding [87]; smoking, prenatal [72]; infection, antenatal [41]; prenatal maternal stress [120]; acetaminophen, prenatal [121]; antibiotic use, prenatal [41]; cesarean section [72]; preterm delivery [72]; folic acid, maternal [122]; vitamin E, maternal intake [123]; vitamin D, sufficient in utero level [124]