Exhaled breath condensate pH assays.

Exhaled breath condensate (EBC) is the only currently available, convenient, noninvasive, ethically acceptable method of assessing airway acidity (pH), especially when it comes to repeated sampling from acutely ill patients. It remains necessary to interpret the data cautiously, because acid at any level in the airway can lead to EBC acidification, and an absence of EBC acidification does not exclude the presence of some degree of airway acidification. EBC pH measures remain the most successful manner to date to evaluate the role of airway acidification in respiratory disease.