EXhaled Hydrogen Peroxide As a Marker of Lung diseasE (EXHALE) Pilot Study.

Inclusion Criteria: * Subject has a clinician made diagnosis of asthma with symptoms for ≥ 3 months supported by objective evidence of airflow variability, reversibility or airway hyper-responsiveness * Subject has a confirmed, clinician made diagnosis of COPD for ≥ 3 months supported by spirometric evidence of fixed airflow limitation (post-bronchodilator ratio of FEV1/FVC \<0.7) recorded at any time * Subject has no known history of lung disease (defined as no current clinical diagnosis of, or be receiving treatment for, a lung disease). * Subject is willing and able to give informed consent for participation in the study. Exclusion Criteria: * Subject has existing co-morbidities that may prevent them from performing spirometry, FeNO or other study measurements (at the discretion of the clinical investigator). * Subject has known other lung, chest wall, neuromuscular, or cardiac disease or abnormality (including end-stage disease or cancer) that would confound symptom scores and spirometry. * Subject has received treatment for an exacerbation of their respiratory disease within the last 2 weeks. * In the opinion of the clinical investigator, participant could be put at risk of harm by having to perform any of the study procedures. * Subject is unable to comprehend the study and provide informed consent, e.g. insufficient command of English in the absence of someone to adequately interpret.