We hypothesized that ( 1 ) children with asymptomatic gastroesophageal reflux determined by 24-hour esophageal pH monitoring would have a lower EBC pH than children without gastroesophageal reflux , ( 2 ) treatment with lansoprazole would alter EBC pH in those children , and ( 3 ) EBC acidification would be associated with increased asthma symptoms , poorer asthma control and quality of life , and increased formation of breath nitrogen oxides ( NOx ) .