A second source of variation between breathomics studies are potential confounders. Indeed, factors known to influence VOCs include age, sex, pregnancy, medication, diet, and smoking, among many others.55‐58 In fact, even very mild exertion can change exhaled volatiles for hours.59,60 This knowledge is important for the interpretation of identified VOCs, but strict avoidance of all potential confounders is likely not worth pursuing. First, there is no evidence that dictating diet and minimizing exertion results in a more reproducible detection of biomarkers. Second, development of more specific and reliable sensor technology will reduce the effect of confounding VOCs on detecting target molecules. Foremost, however, extensive constraints on measurement protocols would render the technique impracticable, whereas its ease of use is central to its attractiveness.