We hypothesized that ( @ ) children with asymptomatic gastroesophageal reflux determined by @-hour esophageal pH monitoring would have a lower EBC pH than children without gastroesophageal reflux , ( @ ) treatment with lansoprazole would alter EBC pH in those children , and ( @ ) EBC acidification would be associated with increased asthma symptoms , poorer asthma control and quality of life , and increased formation of breath nitrogen oxides ( NOx ) .