My lungs are damaged by chemo, i have asthma, my grandma died from lung cancer i've been smoking scine i was thirteen i want to quit how would be safe?

You can if you want: First is your decision , then some support , multiple studies showed that people who had a strong desire and strong decision to quit are successfull, md' scan help you with multiple meds , on you there are two bad things You started at early age when your lung cells are still immature and more prone to get injury , and second you have family history of lung ca , quit and get help of MD.