An 'organic cage molecule' called CC3 has been found to separate krypton, radon and xenon from air at concentrations of only a few parts per million.
Gases such as radon, xenon and krypton all occur naturally in the air but in minute quantities – typically less than one part per million. As a result they are expensive to extract for use in industries such as lighting or medicine and, in the case of radon, the gas can accumulate in buildings.
In the US, radon accounts for around 21,000 lung cancer deaths a year.