Respiratory illness refers to a range of conditions that affect the lungs and airways, making it difficult to breathe. Common examples include asthma, chronic obstructive pulmonary disease (COPD), and pneumonia. These illnesses can be caused by infections, allergies, or exposure to irritants like smoke and pollution. Symptoms of respiratory illness often include coughing, wheezing, shortness of breath, and chest tightness. Diagnosis typically involves physical examinations, imaging tests, and lung function tests. Treatment may include medications, lifestyle changes, and in some cases, oxygen therapy to help improve breathing and overall lung function.