Hello, Thanks for your query on HCM As per your clinical history is concerned please follow like this to know exact cause responsible for mucus in lungs - 1)Do a clinical examination by your treating Doctor and to confirm do a CT scan and a biopsy test. 2)Do take treatment as per underlaying pathological cause only. To prevent risk you can do like this - 1)Don t smoke and if you have this habit then stop smoking. 2)Avoid secondhand smoke. If you live or work with a smoker, urge him or her to quit. At the very least, ask him or her to smoke outside. Avoid areas where people smoke, such as bars and restaurants, and seek out smoke-free options. 3)Avoid carcinogens at work. Take precautions to protect yourself from exposure to toxic chemicals at work. Follow your employer s precautions. For instance, if you re given a face mask for protection, always wear it. Ask your doctor what more you can do to protect yourself at work. 4)Eat a diet full of fruits and vegetables. Choose a healthy diet with a variety of fruits and vegetables. Food sources of vitamins and nutrients are best. Avoid taking large doses of vitamins in pill form, as they may be harmful. 5)Exercise most days of the week. If you don t exercise regularly, start out slowly. Try to exercise most days of the week. Hope that helps