Menthol for Dyspnea Relief in Health and COPD

This study is testing whether inhaling menthol can help relieve the sensation of breathlessness (dyspnea) in healthy people and in people with COPD (chronic obstructive pulmonary disease). Menthol is thought to activate cooling receptors in the airways that may reduce the perception of difficulty breathing. **You may be eligible if (healthy participants):** - You are 18 or older - You have normal lung function and are a non-smoker or have been smoke-free for at least 12 months - You can read and understand Dutch or English **You may be eligible if (COPD participants):** - You have clinically stable COPD (no recent exacerbations requiring antibiotics or steroids in the past 14 days) - You meet the same age and language requirements **You may NOT be eligible if:** - You have active COPD symptoms requiring recent medical treatment - You are a current smoker - You have other lung conditions that could interfere with the study Talk to your doctor to see if this trial is right for you.