Measuring Hydrogen Peroxide in Exhaled Breath Condensate in COPD

Inclusion Criteria: COPD participants: * A diagnosis of COPD. * Not current smokers * Stable COPD (no chest infection requiring antibiotics and/or oral steroids in the past 1 month). * Able to give written informed consent prior to participation in the study including all of its procedures. * Male or female subject aged 18 years and above at screening. * Able to complete the study and all measurements. * Able to read, comprehend, and write at a sufficient level to complete study related materials Healthy subjects: * non-smokers * Healthy individuals, free of significant disease. * Able to give written informed consent prior to participation in the study including all of its procedures. * Able to comply with the requirements and restrictions listed in the consent form. * Male or female subject aged 18 years and above at screening. * Able to complete the study and all measurements. * Able to read, comprehend, and write at a sufficient level to complete study related materials. Exclusion Criteria: COPD Participants: * We will not recruit subjects who lack the capacity to consent. * Current or past diagnosis of asthma. * History of any chronic respiratory diseases other than COPD. * History of another medical condition, which in the opinion of the Unit Physician, contraindicates his/her participation in the study. Unstable respiratory disease in the last four weeks prior to the screening visit (indicated by any change in their maintenance inhaled therapy or who have had a lower respiratory tract infection in the previous four weeks). * Evidence of a respiratory exacerbation requiring emergency room treatment and/or hospitalisation within four weeks before screening. * Use of systemic (oral or intravenous) steroids 4 weeks prior to inclusion (injectable depot steroids 6 weeks) or more than 3 periods during the last 12 months. * Patients who have evidence of alcohol or substance abuse. * Participation in another clinical trial with an investigational drug in the four weeks preceding the screening visit. * Those, in the opinion of the investigator, who may prove non-compliant with study procedures. * History of an upper or lower respiratory infection (including coryza) within 3 weeks of baseline assessments (assessments and entry could be deferred. Healthy subjects: * A history of recreational drug use or allergy which in the opinion of the investigators contra-indicates their participation. * Participation within 3 months in any other study testing a new molecular entity or drug or involving invasive procedures. * Those, in the opinion of the investigator, who may prove non-compliant with study procedures. * History of an upper or lower respiratory infection (including coryza) within 3 weeks of baseline assessments.