Whether the lungs can return to normal after quitting smoking needs to be judged according to a number of factors such as the length of time you have smoked, the amount of cigarettes you have smoked, your age, and the presence of any diseases in your body. If you have been smoking for a short period of time, a few months or one or two years, and you do not smoke a lot, and you are in good physical condition, in this case, your lung function can completely return to normal after quitting smoking. If you have been smoking for a long time and smoke a lot, in most cases, your lungs cannot be reversed after quitting and you cannot return to the state you were in before you did not smoke. Cigarette combustion can produce carbon monoxide, nicotine, smoke tar and other toxic and harmful substances, which can lead to the body’s bronchial mucosa cilia epithelial dysfunction, interstitial fibrosis of lung tissue and other conditions, smoking leads to the lungs occurring in the pathological damage is often unable to recover. Quitting smoking can reduce further damage to the lungs. After stopping smoking, most of the toxic and harmful substances can be excreted through the respiration of the lungs and the excretion of the liver and kidneys, along with the body’s metabolism, so quitting smoking can reduce the accumulation of toxic and harmful substances in the body, thus reducing the stimulation of the lungs.