Multiple chemical sensitivity (MCS) is a complex disorder initiated by chemical exposure, particularly through the airways. MCS patients report sensitivity or intolerance to low levels of a wide spectrum of chemicals. Symptoms could include asthma-like signs, rhinitis, fatigue, cognitive dysfunction, psycho-physiological alteration, and other specific tissue reactions resembling hypoxic and oxidative stress effects. To recognize physiological signs that would allow the diagnosis of MCS in a non-invasive way we investigated the potential application of a new sensor system. In healthy volunteers, we measured exhaled breath content in the control condition and under exposure to olfactory stressors that mimic hypoxic or pollutant stressors playing a potential role in the generation of the MCS disorder. The recording system used is based on metal oxide semiconductor (MOS) sensor having a sensing range of 450-2,000 ppm CO2 equivalents, which is able to detect a broad range of compounds playing a potential role in the generation of the MCS disorder, while correlating directly with the CO2 levels. The results indicate that the recording system employed was suitable for the analysis of exhaled breath content in humans. Interestingly, the system was able to detect and discriminate between the exhaled breath content taken from the control condition and those from conditions under stress that mimicked exposures to pollutant or hypoxia. The results suggest that chronic hypoxia could be involved in the MCS disorder.
