The questionnaire used for data collection was based in part on information described by Campbell et al and on the clinical expertise of the co-investigators. After being critiqued by university-based experts in medicine, nursing and educational psychology, the questionnaire was pilot tested and revised. Questionnaires were administered at the time subjects commenced oxygen therapy (day 0 – baseline data) and daily thereafter. Subjects were asked about five possible symptoms – dry nasal passage, dry mouth, dry throat, headache and chest discomfort – and they rated each symptom according to a five-item Likert scale. Possible responses ranged from asymptomatic to severely symptomatic. Patients also were asked forced choice (Yes/No) questions about the existence of epistaxis, cough and phlegm. Statistical methods: Symptom scores over the two treatment periods were studied using linear mixed effects models to allow for the repeated measures per patients. Explanatory variables included appropriate baseline values as well as terms for treatment, days on treatment, period and interactions involving treatment. A similar approach was taken to analyze dichotomous outcomes, based on the generalized estimating equation approach . Model reduction was based on likelihood ratio and Wald type tests. Treatment effects were assessed using the asymptotic normal distributions of the associated estimates. It’s time to pay less money – just get allergy treatment at the best online pharmacy.