In the study, graduate student Michael Kambourse, working with Blake and Rowland, examined exhaled breath from people with and without cystic fibrosis using laboratory methods developed for their atmospheric chemistry work. In that work, they measure the levels of trace gases in excess of the parts-per-billion range that contribute to local and regional air pollution. Their research group is one of the few in the world recognized for its ability to measure accurately at such small amounts.
In analyzing the breath samples, the researchers monitored levels of three sulfides in the cystic fibrosis patients -- carbonyl sulfide, dimethylsulfide and carbon disulfide. Significantly, they found that cystic fibrosis patients exhaled carbonyl sulfide (OCS) at rates up to 2 times higher than people who don't have the disease, making it an attractive target for future breath analysis.
The study determined that the regular air the test subjects breathed in had about 600 parts-per-trillion volume (pptv) of OCS. The non-cystic fibrosis subjects exhaled a mean average of 350 pptv of OCS, meaning that about 250 pptv of OCS was removed from the inhaled air. The cystic fibrosis subjects exhaled a mean average 490 pptv of OCS, and the three individuals with the weakest pulmonary function exhaled as much as 800 pptv, producing an excess of OCS. This suggests a substantial OCS source, probably bacterial, exists in their lungs, in addition to poorer processing of inhaled gas.
The researchers are continuing their breath-analysis work in areas of autism, diabetes and oral glucose tolerance testing. Most relevant are ongoing studies in which they are testing the profile of gases produced by bacteria, like P. aeruginosa.