Abstract
Breathing air is a fundamental human need, yet its safety, e.g., when challenged by various harmful or lethal substances, is often not properly guarded. Currently, air toxicity is monitored only for single or limited number of known toxicants, thus failing to fully warn against possible hazardous air. Here, using a photoionization detector (PID) or GC-MS/FID we found that within minutes living rats emitted distinctive profiles of volatile organic compounds (VOCs) via breath when exposed to various airborne toxicants such as endotoxin, O3, ricin, and CO2. Compared to background indoor air, when exposed to ricin or endotoxin aerosols breath-borne VOC levels, especially that of carbon disulfide, were shown to decrease, while elevated levels were observed for O3 and CO2 exposures. Principal component analysis (PCA) revealed a clear contrast in breath-borne VOCs profiles of rats among different toxicant exposures. MicroRNA regulations such as miR-33, miR-146a and miR-155 from rats’ blood samples also suggested varying mechanisms used by the rats in combating different air toxicant challenges. By integrating living rats, breath sampling, and VOC online detection, we pioneered a system that can real-time monitor air toxicity without the need of detecting specific species. Importantly, rats were shown to be able to sniff off toxic air.