Her thesis project was measuring the three stable isotopes of oxygen in carbon monoxide, with the idea of being able to identify the sources of this gas in the troposphere. Carbon monoxide can be deadly in more ways than the usual one. It is a principle molecule in the reactions that form smog. A carbon monoxide molecule in the lower atmosphere has a lifetime of from one to three months. During that time it can enter into reactions that produce ugly air conditions.
Carbon monoxide is produced by many human activities, as well as by some natural ones.
The object of her work was to isotopically characterize the different sources of carbon monoxide in order to distinguish the several sources. When she entered into this project she was aware that two other groups had, to their satisfaction, worked up a scheme to identify carbon monoxide sources. But her method was different. Her method also produced different results. She was able to show that one major source, automobiles, did not produce carbon monoxide with a very specific isotopic signature, as these groups had contended.