 Participants undergo blood tests and breathing tests. For the latter, participants breathe into a machine before and after inhaling an asthma medication called albuterol. The machine measures the volume of air the subject can breathe out. Participants also provide a sample of exhaled breath by breathing normally for up to 30 minutes while wearing a mask devised for the procedure. Pulse rate, oxygen saturation and wheezing are monitored during the breath collection... 