Stable, specific 'breathprints' unique to an individual exist and may have applications as diagnostic tools in personalized medicine, according to research published in the open access journal PLOS ONE by Renato Zenobi and colleagues from the Swiss Federal Institute of Technology (ETH) and the University Hospital Zürich, Switzerland.

The researchers studied the chemicals present in exhaled breath from eleven participants, collected at different times of the day over an 11-day period. They found significant differences in the chemicals present in each person's samples, and discovered differences between samples taken at different times of day from the same person. Despite these variations, their results identified a core 'breathprint' unique to each individual that was highly specific and could be linked to its owner. The factors that contribute to this unique breathprint are still unknown.

The authors suggest that attributes like diet, health conditions or exposure to other chemicals may contribute to these individual signatures of breath. According to the study, these results suggest that breath analysis may eventually become a valuable source of clinical information, similar to the analysis of other fluids such as plasma or urine.